Continuously variable transmission apparatus

ABSTRACT

A continuously variable transmission apparatus includes a toroidal continuously variable transmission, a planetary gear transmission and a clutch apparatus that connects the toroidal continuously variable transmission and the planetary gear transmission. The clutch apparatus includes: a low speed clutch a high speed clutch and a controller. The controller controls the transmission ratio of the toroidal continuously variable transmission so that rotational speeds of members connected via the clutch apparatus equals with each other, and then disengages the one of the low speed clutch and the high speed clutch after engaging the other, whereby an instance of simultaneously transmitting the power by the two clutches is set during a time period until disconnecting the other clutch after starting to transmit the power by the one clutch.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improvement in a continuouslyvariable transmission apparatus utilized as an automatic transmissionfor a vehicle (automobile) and integrated with a toroidal-typecontinuously variable transmission apparatus realizing a structurecapable of preventing a state of bringing about an abrupt variation in atransmission ratio when switching a low speed mode and a high speed modeat low cost.

2. Background Art

As an automatic transmission apparatus for a vehicle, researches arecarried out on using a toroidal-type continuously variable transmissionas shown by FIGS. 27 through 29 and the transmission is partiallyembodied. The toroidal-type continuously variable transmission isreferred to as a double cavity type and input side disks 2, 2 aresupported by surroundings of both end portions of an input shaft 1 viaball splines 3, 3. Therefore, the two input side disks 2, 2 aresupported concentrically and synchronizingly rotatably. Further, anoutput gear 4 is supported at a surrounding of a middle portion of theinput shaft 1 rotatably relative to the input shaft 1. Further, outputside disks 5, 5 are engaged to both end portions of a cylindricalportion provided at a central portion of the output gear 4 respectivelyby splines. Therefore, the two output side disks 5, 5 aresynchronizingly rotated along with the output gear 4.

Further, respective pluralities of pieces (normally, two through threepieces respectively) of power rollers 6, 6 are interposed between therespective input side disks 2, 2 and the respective output side disks 5,5. The respective power rollers 6, 6 are respectively supportedrotatably by inner side faces of trunnions 7, 7 via support shafts 8, 8and a plurality of rolling bearings. The respective trunnions 7, 7 arerockably displaceable centering on pivoting shafts 9, 9 provided at therespective trunnions 7, 7 concentrically with each other at both endportions in respective length directions (up and down direction of FIGS.27, 29 and head and tail direction of FIG. 28). A motion of incliningthe respective trunnions 7, 7 is carried out by displacing therespective trunnions 7, 7 in axial directions of the pivoting shafts 9,9 by hydraulic type actuators 10, 10 and inclined angles of all of thetrunnions 7, 7 are synchronized with each other hydraulically andmechanically.

That is, when the inclined angles of the respective trunnions 7, 7 arechanged in order to change a transmission ratio between the input shaft1 and the output gear 4, the respective trunnions 7, 7 are displaced bythe respective actuators 10, 10 respectively in reverse directions (samedirection with regard to directions of rotating the respective disks 2,5), for example, the power roller 6 on a right side of FIG. 18 isdisplaced to a lower side of the drawing and the power roller 6 on aleft side of the drawing is displaced to an upper side of the drawingrespectively. As a result, directions of forces in tangential linesacting on rolling contact portions (traction portions) betweenperipheral faces of the respective power rollers 6, 6 and the inner sidefaces of the respective input side disks 2, 2 and the respective outputside disks 5, 5 are changed (side slip is produced at the contactportion). Further, in accordance with the change in the directions ofthe forces, the respective trunnions 7, 7 are rocked (inclined) indirections reverse to each other centering on the pivoting shafts 9, 9axially supported by support plates 11, 11. As a result, contactpositions between the peripheral faces of the respective power rollers6, 6 and the inner side faces of the respective input side and outputside disks 2, 5 are changed and a rotational transmission ratio betweenthe input shaft 1 and the output gear 4 is changed.

A state of charging and discharging a pressurized oil to and from therespective actuators 10, 10 is controlled by a single piece of controlvalve 12 regardless of a number of the respective actuators 10, 10 andmovement of any single piece of trunnion 7 is fed back to the controlvalve 12. The control valve 12 includes a sleeve 14 displaced by astepping motor 13 in an axial direction (head and tail direction of FIG.27, left and right direction of FIG. 29) and a spool 15 fit to an innerdiameter side of the sleeve 14 displaceably in the axial direction.Further, in rods 17, 17, connecting the respective trunnions 7, 7 andpistons 16, 16 of the actuators 10, 10, an end portion of the rod 17belonging to any single piece of the trunnion 7 is fixed with a precesscam 18 and there is constituted a feedback mechanism for transmittingmovement of the rod 17, that is, a synthesized value of a displacementamount in an axial direction and a displacement amount in a rotationaldirection to the spool 15 via the precess cam 18 and a link arm 19.Further, a synchronizing cable 20 is hung between the respectivetrunnions 7, 7 to thereby mechanically synchronize the inclined anglesof the respective trunnions 7, 7 even in a failure in a hydraulicsystem.

In switching a speed changing state, a flow path in a predetermineddirection of the control valve 12 is opened by displacing the sleeve 14to a predetermined position compatible with a desired transmission ratioby the stepping motor 13. As a result, a pressurized oil is fed in thepredetermined direction to the respective actuators 10, 10 and therespective actuators 10, 10 displace the trunnions 7, 7 in thepredetermined direction. That is, in accordance with feeding thepressurized oil, the respective trunnions 7, 7 are rocked centering onthe respective pivoting shafts 9, 9 while being displaced in axialdirections of the respective pivoting shafts 9, 9. Further, movement (inaxial direction and rocking displacement) of any single piece of thetrunnion 7 is transmitted the spool 15 via a cam surface 21 of theprecess cam 18 fixed to the end portion of the rod 17 and the link arm19 to displace the spool 15 in the axial direction. As a result, in astate of displacing the trunnion 7 by a predetermined amount, the flowpath of the control valve 12 is closed and the pressurized oil isstopped from charging and discharging to and from the respectiveactuators 10, 10.

In operating the above-described toroidal-type continuously variabletransmission, the input side disk 2 on one side (left side of FIGS. 27,28) is driven to rotate by a drive shaft 22 connected to a power sourceof an engine or the like via a press apparatus 23 of a loading cam type,or a hydraulic type as illustrated. As a result, the pair of input sidedisks 2, 2 supported by the both end portions of the input shaft 1 arerotated synchronizingly while being pressed in directions proximate toeach other. Further, the rotation is transmitted to the respectiveoutput side disks 5, 5 via the respective power rollers 6, 6 andoutputted from the output gear 4.

In the case in which rotational speeds of the input shaft 1 and theoutput gear 4 are changed, first, when the speed is reduced between theinput shaft 1 and the output gear 4, the respective trunnions 7, 7 aremoved in the axial directions of the respective pivoting shafts 9, 9 bythe respective actuators 10, 10 to rock to positions shown in FIG. 28.Further, as shown by FIG. 28, the peripheral faces of the respectivepower rollers 6, 6 are made to be respectively brought into contact withportions of the respective input side disks 2, 2 on sides of centers ofthe inner side faces and portions of the respective outputs side disks5, 5 on sides of outer peripheries of the inner side faces. On thecontrary, in increasing the speed, the respective trunnions 7, 7 arerocked in directions opposed to those of FIG. 28 and contrary to a stateshown in FIG. 28, the respective trunnions 7, 7 are inclined such thatthe peripheral faces of the respective power rollers 6, 6 arerespectively brought into rolling contact with portions of therespective input side disks 2, 2 on sides of the outer peripheries inthe inner side surfaces thereof and portions of the respective outputside disks 5, 5 on sides of the centers of the inner side faces thereof.A middle transmission ratio (speed ratio) is provided between the inputshaft 1 and the output gear 4 when the inclined angles of the respectivetrunnions 7, 7 are set to middles.

Further, when the toroidal-type continuously variable transmissionconstituted and operated as described above is actually integrated to acontinuously variable transmission for an automobile, it has beenvariously proposed in a background art to constitute a continuouslyvariable transmission apparatus by being integrated with a planetarygear mechanism. FIG. 30 shows the continuously variable transmissionapparatus proposed in the prior art disclosed in U.S. Pat. No.6,251,039. The continuously variable transmission apparatus is referredto as so-to-speak geared neutral, in which a rotational state of anoutput shaft can be switched to rotate regularly and rotate reversely byinterposing a stationary state while rotating the input shaft in onedirection and which is constituted by a toroidal-type continuouslyvariable transmission 24 and a planetary gear type transmission 25. Thetoroidal-type continuously variable transmission 24 is provided with theinput shaft 1, the pair of input side disks 2, 2, the output side disk 5a and the plurality of power rollers 6, 6. In the illustrated example,the output side disk 5 a is constituted by a structure of butting outerside faces of the pair of output side disks to integrate.

The planetary gear type transmission 25 is provided with a carrier 26coupled to fix to the input shaft 1 and the input side disk 2 on oneside (right side of FIG. 30). A first transmitting shaft 28 both endportions of which are respectively provided fixedly with planetary gearelements 27 a, 27 b is rotatably supported by a middle portion in adiameter direction of the carrier 26. Further, a second transmittingshaft 31 both end portions of which are fixedly provided with sun gears29 a, 29 b is supported rotatably on a side opposed to the input shaft 1by interposing the carrier 26 therebetween concentrically with the inputshaft 1. Further, each of the planetary gear elements 27 a, 27 b and asun gear 32 fixedly provided to a front end portion (right end portionof FIG. 30) of a hollow rotating shaft 32 a base end portion (left endportion of FIG. 30) is coupled with the output side disk 5 a or the sungear 29 a fixedly provided to one end portion (left end portion of FIG.30) of the second transmitting shaft 30 are respectively brought in meshwith each other. Further, the planetary gear element 27 a on one side(left side of FIG. 30) is brought in mesh with a ring gear 34 rotatablyprovided at a surrounding of the carrier 26 via other planetary gearelement 33.

Meanwhile, planetary gear elements 36 a, 36 b are rotatably supported bya second carrier 35 provided at a surrounding of the sun gear 29 bfixedly provided to other end portion (right end portion of FIG. 30) ofthe second transmitting shaft 30. Further, the second carrier 35 isfixedly provided to a base end portion (left end portion in FIG. 30) ofan output shaft 37 arranged concentrically with the input shaft 1 andthe second transmitting shaft 30. Further, the respective planetary gearelements 36 a, 36 b are brought in mesh with each other, the planetarygear element 36 a on one side is brought in mesh with the sun gear 29 b,and the planetary gear element 36 b on other side is brought in meshwith a second ring gear 38 provided rotatably at a surrounding of thesecond carrier 35, respectively. Further, the ring gear 34 and thesecond carrier 35 are made to be engageable and disengageable by a lowspeed clutch 39, and the second ring gear 38 and a fixed portion of ahousing or the like are made to be engageable and disengageable by ahigh speed clutch 40.

In the case of the above-described continuously variable transmissionapparatus shown in FIG. 30, in a so-to-speak low speed mode stateconnecting the low speed clutch 39 and disconnecting the high speedclutch 40, power of the input shaft 1 is transmitted to the output shaft37 via the ring gear 34. Further, by changing a transmission ratio ofthe toroidal-type continuously variable transmission 24, a transmissionratio as a total of the continuously variable transmission apparatus,that is, a transmission ratio between the input shaft 1 and the outputshaft 37 is changed. In such a low speed mode state, the transmissionratio of the total of the continuously variable apparatus is changedinfinitely. That is, by adjusting the transmission ratio of thetoroidal-type continuously variable transmission 24, while bringing theinput shaft 1 in a state of being rotated in one direction, a rotationalstate of the output shaft 37 can be converted to regular rotation andreverse rotation by interposing a stationary state.

Further, in running at an accelerated speed or a constant speed in sucha low speed mode state, a torque (passing torque) passing thetoroidal-type continuously variable transmission 24 is applied from theinput shaft 1 to the output shaft disk 5 a via the carrier 26, the firsttransmitting shaft 28, the sun gear 32 and the hollow rotating shaft 31and is applied from the output side disk 5 a to the respective inputside disks 2, 2 via the respective power rollers 6, 6. That is, thetorque passing the toroidal-type continuously variable transmission 24in running at the accelerated speed or the constant speed is circulatedin a direction in which the respective input side disks 2, 2 receive thetorque from the respective power rollers 6, 6.

In contrast thereto, in a so-to-speak high speed mode state in which thelow speed clutch 39 is disconnected and the high speed clutch 40 isconnected, the power of the input shaft 1 is transmitted to the outputshaft 37 via the first and the second transmitting shafts 28, 30.Further, by changing the transmission ratio of the toroidal-typecontinuously variable transmission 24, the transmission ratio as thetotal of the continuously variable transmission apparatus is changed. Inthis case, the larger the transmission ratio of the toroidal-typecontinuously variable transmission 24, the larger the transmission ratioof the total of the continuously variable transmission apparatus. Inrunning at an accelerated state or a constant speed in such a high speedmode state, a torque passing the toroidal-type continuously variabletransmission 25 is applied from the respective input side disks 2, 2 tothe output side disk 5 a via the respective power rollers 6, 6.

Further, U.S. Pat. No. 6,171,210 discloses a continuously variabletransmission apparatus as shown by FIG. 31. The continuously variableapparatus is referred to as so-to-speak power split type and constitutedby combining a toroidal-type continuously variable transmission 24 a anda planetary gear type transmission 25 a. Further, in a low speed mode,power is transmitted only by the toroidal-type continuously variabletransmission 24 a and in a high speed mode, power is mainly transmittedby the planetary gear type transmission 25 a and a transmission ratio bythe planetary gear type transmission 25 a is controlled by changing atransmission ratio of the toroidal-type continuously variabletransmission 24 a.

Therefore, a base end portion (right end portion of FIG. 31) of theinput shaft 1 that extends through the center portion of thetoroidal-type continuously variable transmission 24 a and supports thepair of input side disks 2, 2 at both end portions thereof and a ringgear 41 constituting the planetary gear type transmission 25 a arecoupled via the high speed clutch 40 a. Further, a starting clutch 44and a hydraulic type pressing apparatus 23 a are provided in a directionof transmitting power in series with each other between an output sideend portion (right end portion of FIG. 31) of a crankshaft 43 of anengine 42 constituting a drive source and an input side end portion(=base end portion=left end portion of FIG. 31) of the input shaft 1.The pressing apparatus 23 a is constituted by fitting the input sidedisk 2 on the base end side into a cylinder 96 in oil tight and to beable to transmit a rotating force.

Further, an output shaft 37 a for outputting power based on rotation ofthe input shaft 1 is arranged concentrically with the input shaft 1.Further, the planetary gear type transmission 25 a is provided at asurrounding of the output shaft 37 a. A sun gear 45 constituting theplanetary gear type transmission 25 a is fixed to an input side endportion (left end portion of FIG. 31) of the output shaft 37 a.Therefore, the output shaft 37 a is rotated in accordance with rotationof the sun gear 45. The ring gear 41 is supported at a surrounding ofthe sun gear 45 concentrically with the sun gear 45 and rotatably.Further, a plurality of sets of planetary gear elements 46 a and 46 bare provided between an inner peripheral face of the ring gear 41 and anouter peripheral face of the sun gear 45. The respective sets of theplanetary gear elements 46 a and 46 b are brought in mesh with eachother, the planetary gear elements 46 a arranged on an outer diameterside are brought in mesh with the ring gear 41 and the planetary gearelements 46 b arranged on an inner diameter side are brought in meshwith the sun gear 45. The respective planetary gear elements 46 a and 46b are rotatably supported by a carrier 47. Further, the carrier 47 isrotatably supported by a middle portion of the output shaft 37 a.

Further, the carrier 47 and the pair of output side disks 5, 5constituting the toroidal-type continuously variable transmission 24 aare connected in a state of being capable of transmitting the rotatingforce by a first power transmitting mechanism 48. The first powertransmitting mechanism 48 is constituted by coupling both end portionsof a transmitting shaft 49 and the respective output side disks 5, 5 orthe carrier 47 by a chain transmitting mechanism or a gear transmittingmechanism. Further, the carrier 47 is rotated by a speed in accordancewith a transmission ratio of the chain transmitting mechanism or thegear transmitting mechanism in accordance with rotation of therespective output side disks 5, 5 in a direction reverse to that of theoutput side disks 5, 5. Meanwhile, the input shaft 1 and the ring gear41 are made to be connectable in a state of capable of transmitting therotating force via other transmitting shaft 50 disposed concentricallywith the input shaft 1 and the high speed clutch 40 a. Therefore, thetransmitting shaft 50 is rotated in a direction and at a speed the sameas those of the input shaft 1 in connecting the high speed clutch 40 a.

Further, a low speed clutch 39 a is provided between an outer peripheraledge portion of the carrier 47 and one end portion (right end portion ofFIG. 31) in the axial direction of the ring gear 41. Further, a reverseclutch 51 is provided between the ring gear 41 and a fixed portion of ahousing (not illustrated) of the continuously variable transmissionapparatus or the like.

According to the continuously variable transmission apparatusconstituted as described above, first, in the low speed mode state, thelow speed clutch 39 a is connected and the high speed clutch 40 a andthe reverse clutch 51 are disconnected. When the starting clutch 44 isconnected under the state and the input shaft 1 is rotated, only thetoroidal-type continuously variable transmission 24 a transmits powerfrom the input shaft 1 to the output shaft 37 a. In running at low speedin this way, the transmission ratio between the respective pairs ofinput side disks 2, 2 and the output side disks 5, 5 is controlledsimilar to the case of a single one of the above-described toroidal-typecontinuously variable transmission shown in FIGS. 27 through 29.Further, in accelerating or running at constant speed in theabove-described low speed mode state, a torque passing the toroidal-typecontinuously variable transmission 24 a is transmitted from therespective above-described input side disks 2, 2 to the respectiveabove-described disks 5, 5 via the respective power rollers.

In contrast thereto, in the high speed mode state, the above-describedhigh speed clutch 40 a is connected and the above-described low speedclutch 39 a and the reverse clutch 51 are disconnected. When the inputshaft 1 is rotated under the state, power is transmitted from the inputshaft 1 to the output shaft 37 a by the transmitting shaft 50 and theplanetary gear type transmission 25 a. That is, when the input shaft 1is rotated in running at high speed as described above, the rotation istransmitted to the ring gear 41 via the high speed clutch 40 a and thetransmitting shaft 50. Further, rotation of the ring gear 41 istransmitted to the sun gear 45 via the plurality of sets of planetarygear elements 46 a and 46 b to rotate the output shaft 37 a fixed withthe sun gear 45. When revolving speed of the respective planetary gearelements 46 a and 46 b is changed by changing the transmission ratio ofthe toroidal-type continuously variable transmission 24 a, atransmission ratio of a total of the continuously variable transmissionapparatus can be controlled.

That is, in the high speed mode state, the slower the revolving speed ofthe respective planetary gear elements 46 a and 46 b, the faster becomesthe rotating speed of the output shaft 37 a fixed with the sun gear 45.Therefore, in the high speed mode state, the more changed thetransmission ratio of the toroidal-type continuously variabletransmission 24 a to a speed reducing side, the more changed is thetransmission ratio of the total of the continuously variabletransmission apparatus to a speed increasing side. In such a state ofrunning at high speed, the toroidal-type continuously variabletransmission 24 a is applied with the torque not from the input sidedisk 2 but from the output side disk 5 (applied with a minus torque whenthe torque applied at low speed is constituted by a plus torque). Thatis, in the state of connecting the high speed clutch 40 a, the torquetransmitted from the engine 42 to the input shaft 1 is transmitted tothe ring gear 41 of the planetary gear type transmission 24 a via thetransmitting shaft 50. Therefore, a torque transmitted from the side ofthe input shaft 1 to the respective input side disks 2, 2 constitutingthe toroidal-type continuously variable transmission 24 a is almostnullified.

Meanwhile, a portion of the torque transmitted to the ring gear 41 viathe transmitting shaft 50 is transmitted from the respective planetarygear elements 46 a and 46 b to the respective output side disks 5, 5 viathe carrier 47 and the first power transmitting mechanism 48. In thisway, the more changed is the transmission ratio of the toroidal-typecontinuously variable transmission 24 a to the speed reducing side, thesmaller the torque applied from the output side disks 5, 5 to thetoroidal-type continuously variable transmission 24 a in order to changethe transmission ratio of the total of the continuously variabletransmission apparatus to the speed increasing side. As a result, inrunning at high speed, the torque inputted to the toroidal-typecontinuously variable transmission 24 a is reduced, a transmittingefficiency of the total of the continuously variable transmissionapparatus is increased, and durability of constituent parts of thetoroidal-type continuously variable transmission 24 a can be promoted.In accelerating or running at constant speed under the high speed modestate, the torque passing the toroidal-type continuously variabletransmission 24 a is transmitted from the respective output side disks5, 5 to the respective input side disks 2, 2 via the respective powerrollers.

Further, when the output shaft 37 a is rotated reversely in order toback up the automobile, both of the low speed and the high speedclutches 39 a and 40 a are disconnected and the reverse clutch 51 isconnected. As a result, the ring gear 41 is fixed, and the respectiveplanetary gear elements 46 a and 46 b are revolved at a surrounding ofthe sun gear 45 while being brought in mesh with the ring gear 41 andthe sun gear 45. Further, the sun gear 45 and the output shaft 37 afixed with the sun gear 45 are rotated in a direction reverse to that inrunning at low speed, mentioned above, and in running at high speed,mentioned above.

In the case of the continuously variable transmission apparatusconstituted by combining the toroidal-type continuously variabletransmission 24 or 24 a and the planetary gear type transmission 25 or25 a via the clutch apparatus and having the low speed mode and the highspeed mode, regardless of whether the continuously variable transmissionapparatus is constituted by the above-described geared neutral type orthe above-described power split type, in switching the low speed modeand the high speed mode, the magnitude and the direction of the torquepassing the toroidal-type continuously variable transmission 24 or 24 aare rapidly changed. Meanwhile, respective constituent members of thetoroidal-type continuously variable transmission 24 or 24 a is displacedor elastically deformed in a direction in accordance with the directionof the torque in accordance with the magnitude of the torque passing theapparatus (passing torque). Further, in accordance with the displacementor the elastic deformation, there is produced so-to-speak torque shiftin which the transmission ratio of the toroidal-type continuouslyvariable transmission 24 or 24 a is changed.

Therefore, when any measure is not taken therefor, in switching themodes of the continuously variable transmission apparatus, thetransmission ratio of the total of the continuously variabletransmission apparatus is rapidly varied by the torque shift. When thetransmission ratio is varied in this way, a speed change shock isbrought about to give unpleasant feeling to a passenger starting from adriver and to cause to deteriorate a part of a system of transmittingpower and therefore, the rapid variation is not preferable. In contrastthereto, there is disclosed a technology of preventing rapid variationof the transmission ratio in switching the mode in U.S. Pat. No.6,074,320, JP-A-2001-50375, JP-A-2001-50380, JP-A-2001-235022, and U.S.Pat. No. 6,569,051, JP-A-9-210191, JP-A-11-108148 which have been knownconventionally.

Among them, according to a prior art described in U.S. Pat. No.6,074,320, the mode is switched in a state in which a rotating speed ofpower inputted to a planetary gear type transmission via a toroidal-typecontinuously variable transmission and a rotating speed of powerinputted to the planetary gear type transmission without passing thetoroidal-type continuously variable transmission coincide with eachother. Further, according to prior arts described in JP-A-2001-50375,JP-A-2001-50380 and JP-A-2001-235022, in switching modes, connection anddisconnection of respective clutches are switched in semi-clutchedstate. Further, according to the prior art described in U.S. Pat. No.6,569,051, modes are switched by electromagnetic clutches. Further,according to the described background art, a switching valve of a spoolvalve type for controlling to charge and discharge pressurized oil toand from the two clutches for low speed and for high speed is providedwith a position of introducing hydraulic pressure to the two clutches inaddition to positions for introducing hydraulic pressure to either oneof the clutches and stopping to introduce hydraulic pressure to other ofthe clutches. In the case of the described background art, atransmission ratio of a toroidal type continuously variable transmissionin switching a mode is restricted to be less than a predetermined value.

According to the prior art preventing rapid variation of thetransmission ratio in switching modes in which modes are switched in thestate in which the rotating speeds coincide with each other as disclosedin U.S. Pat. No. 6,074,320, the rapid variation of the transmissionratio based on the torque shift cannot be prevented only thereby.Further, in the case of switching connection and disconnection of therespective clutches in the semi-clutched state as disclosed inJP-A-2001-50375, JP-A-2001-50380 and JP-A-2001-235022, a delicatecontrol is needed, a total of the apparatus is complicated, cost isincreased and also danger of failure is enhanced. Further, in the caseof switching modes by the electromagnetic clutches disclosed in U.S.Pat. No. 6,069,051, not only rapid variation of the transmission ratiobased on the torque shift cannot be prevented only thereby but alsodanger of failure is enhanced.

SUMMARY OF THE INVENTION

In view of the above-described circumstance, the invention has been madeto realize a structure at a low cost, in which an occurrence of anabrupt variation in reduction rate can be surely prevented whenswitching a low speed mode and a high speed mode, and in which a failuredoes not easily occur.

Further, in the case of a structure of selecting a state of connectingeither one of clutches and a state of connecting two clutches by asingle piece of switching valve as described in JP-A-9-210191, thefollowing problems (1) through (3) are posed.

(1) Owing to the structure of simultaneously introducing hydraulicpressure into hydraulic chambers for clutches for connecting the twoclutches in order to simultaneously fasten the clutch for low speed andthe clutch for high-speed in switching the mode, a time period requiredfor switching the mode is prolonged to cause to give a strange feelingto a driver. Particularly, in the case of the structure described inJP-A-9-210191, the hydraulic pressure is simultaneously introduced tothe two clutches by the switching valve, however, it cannot beguaranteed that the two clutches are connected so far as a time periodto some degree has not elapsed after switching the switching valve byinfluence of resistance of a hydraulic pressure introducing path portionand a stroke of a piston belonging to the clutch. Therefore, in order toensure a state of simultaneously connecting the two clutches, the timeperiod required for switching the mode is obliged to be prolonged.(2) By similar reason, an amount of pressurized oil necessary forswitching the mode is increased, an amount of working a pump forsupplying the pressurized oil is increased and an efficiency of a totalof a continuously variable transmission apparatus is reduced.(3) In order to select either of the states, it is necessary toaccurately control a position of the spool constituting the switchingvalve. Specifically, in switching the mode, in the midst of displacingthe spool from one end to other end in an axial direction, aftertemporarily stopping the spool at a center position, the spool needs tomove again in the same direction. A control for moving the spool in thisway is troublesome and a danger of failure is enhanced.

Further, in the case of the background art described in JP-A-11-108148,torque shift accompanied by switching the mode is not prevented.

The invention provides a continuously variable transmission apparatuscombined with a toroidal type continuously variable transmission and aplanetary gear type transmission via a clutch apparatus, wherein theclutch apparatus comprising: a low speed clutch connected in realizing alow speed mode of increasing a gear change ratio of the continuouslyvariable transmission apparatus and disconnected in realizing a highspeed mode of reducing the gear change ratio of the continuouslyvariable transmission apparatus; a high speed clutch connected inrealizing the high speed mode and disconnected in realizing the lowspeed mode; and a controller for switching a state of connecting anddisconnecting the respective clutches; and wherein the controller bringsa speed change state into either mode of the low speed mode and the highspeed mode by controlling to connect and disconnect the respectiveclutches; and the controller has a function, in switching the low speedmode and the high speed mode, that, prior to start to connect one of thelow speed clutch and the high speed clutch which has not been connected,by adjusting the transmission ratio of the toroidal type continuouslyvariable transmission, the one clutch is started to connect after makingrotational speeds of a pair of members connected via the one clutchsubstantially coincide with each other, and after starting to transmit apower by the one clutch, an operation of disconnecting other clutchwhich has been connected is started, whereby an instance ofsimultaneously transmitting the power by the two clutches is set duringa time period until disconnecting the other clutch after starting totransmit the power by the one clutch.

Preferably, a start of the power transmission by the one clutch isdetected by detecting a displacement of a drive member for connectingthe clutch.

Preferably, the low speed clutch is connected by introducing a hydraulicpressure into a hydraulic chamber for the low speed clutch; the highspeed clutch is connected by introducing a hydraulic pressure into ahydraulic chamber for the high speed clutch; and the power is detectedto start to transmit by the one clutch of the low speed clutch and thehigh speed clutch by the hydraulic pressure in the hydraulic chamber forthe clutch for introducing the hydraulic pressure in connecting theclutch.

Preferably, the hydraulic pressure in the hydraulic chamber for theclutch is electrically detected by a pressure sensor.

Preferably, the continuously variable transmission apparatus furtherincludes: a switching valve switched by introducing the hydraulicpressure into the hydraulic chamber for the clutch to mechanicallydetect the hydraulic pressure in the hydraulic chamber for the clutch;wherein a spool constituting the switching valve is displaced byintroducing the hydraulic pressure into the hydraulic chamber for theclutch and the hydraulic pressure introduced into the hydraulic chamberfor the clutch of the other clutch is reduced based on a displacement ofthe spool.

Preferably, a state of introducing the hydraulic pressure into thehydraulic chamber for the low speed clutch is controlled by theswitching valve for the low speed clutch including a spool for the lowspeed clutch displaced by introducing the hydraulic pressure into apilot chamber for the low speed clutch; a state of introducing thehydraulic pressure into the hydraulic chamber for the high speed clutchincluding a spool for the high speed clutch displaced by introducing thehydraulic pressure into a pilot chamber for the high speed clutch; thestate of introducing the hydraulic pressure into the pilot chamber forthe low speed clutch and the state of introducing the hydraulic pressureinto the pilot chamber for the high speed clutch are controlled by anelectric switch valve; the switching valve for the low speed clutchreduces the hydraulic pressure introduced into the hydraulic chamber forthe low speed clutch by introducing the hydraulic pressure into thepilot chamber for the low speed clutch; the hydraulic pressureintroduced into the pilot chamber for the low speed clutch is thehydraulic pressure introduced into the hydraulic chamber for the highspeed clutch; the switching valve for the high speed clutch reduces thehydraulic pressure introduced into the hydraulic chamber for the highspeed clutch by introducing the hydraulic pressure into the pilotchamber for the high speed clutch; and the hydraulic pressure introducedinto the pilot chamber for the high speed clutch is the hydraulicpressure introduced into the hydraulic chamber for the low speed clutch.

Preferably, a state of introducing the hydraulic pressure into thehydraulic chamber for the low speed clutch is controlled by the switchvalve for the low speed clutch including a spool for the low speedclutch displaced by introducing the hydraulic pressure into a pilotchamber for the low sped clutch; a state of introducing the hydraulicpressure into the hydraulic chamber for the high speed clutch iscontrolled by the switching valve for the high speed clutch including aspool for the high speed clutch displaced by introducing the hydraulicpressure into a pilot chamber for the high speed clutch; the state ofintroducing the hydraulic pressure into the pilot chamber for the lowspeed clutch and the state of introducing the hydraulic pressure intothe pilot chamber for the high speed clutch are controlled by a shiftingswitching valve including a switching spool displaced by introducing thehydraulic pressure into a switching pilot chamber; a state ofintroducing the hydraulic pressure into the switching pilot chamber iscontrolled by a shifting electric switching valve, the switching valvefor the low speed clutch reduces the hydraulic pressure introduced intothe hydraulic chamber for the low speed clutch by introducing thehydraulic pressure into the pilot chamber for the low speed clutch; thehydraulic pressure introduced into the pilot chamber for the low speedclutch is the hydraulic pressure introduced into the hydraulic chamberfor the high speed clutch; the switching valve for the high speed clutchreduces the hydraulic pressure introduced into the hydraulic chamber forthe high speed clutch by introducing the hydraulic pressure into thepilot chamber for the high speed clutch; and the hydraulic pressureintroduced into the pilot chamber for the high speed clutch is thehydraulic pressure introduced into the hydraulic chamber for the lowspeed clutch.

Preferably, the switching valve for the high speed clutch includes anelastic member for the high speed clutch on a side opposed to the pilotchamber for the high speed clutch in an axial direction by interposingthe spool for the high speed clutch; the spool for the high speed clutchis displaced against an elastic force of the elastic member for the highspeed clutch by introducing the hydraulic pressure into the pilotchamber for the high speed clutch; the switching valve for the low speedclutch includes an elastic member for the low speed clutch on a sideopposed to the pilot chamber for the low speed clutch in an axialdirection by interposing the spool for the low speed clutch; and thespool for the low speed clutch is displaced against an elastic force ofthe elastic member for the low speed clutch by introducing the hydraulicpressure into the pilot chamber for the low speed clutch.

Preferably, the elastic force of the elastic member for the clutchintegrated to the switching valve for the clutch opened in introducingthe hydraulic pressure into the hydraulic chamber for the clutchbelonging to the clutch which is not to be connected at least instarting in the respective switching valves for the low speed and thehigh speed clutches is set to be large in a running state and small in anon-running state.

Preferably, the elastic member for the clutch is a compression coilspring for the clutch, the compression coil spring for the clutch isprovided between the spool for the clutch and a pressing piston provideddisplaceably in the axial direction at inside of a cylinder portionprovided at a position opposed to the pilot chamber for the clutch inthe axial direction by interposing the spool for the clutch, and thepressing piston increases the elastic force of the compression coilspring for the clutch by being displaced to a side of the spool for theclutch by the hydraulic pressure introduced into the cylinder portionwhen the running state is selected and reduces the elastic force of thecompression coil spring for the clutch by being displaced to a side ofbeing remote from the spool for the clutch when the hydraulic pressurein the cylinder portion is discharged by selecting the non-runningstate.

Preferably, the continuously variable transmission apparatus furtherincludes: a manual switching valve switched to a running mode and anon-running mode by a shift lever installed at a driver's seat; whereinalso the elastic forces of the elastic members for the clutchesintegrated to the switching valves for the clutches opened inintroducing the hydraulic pressure into the hydraulic chambers for theclutches belonging not only to the clutch which is not to be connectedin starting but also the clutch which is to be connected in starting forelastically pressing the spools for the clutches in the respectiveswitching valves for the low speed and the high speed clutches areincreased in a state of switching the manual switching valve to therunning mode and reduced in a state of switching the manual switchingvalve to the non-running mode.

Preferably, the switching valve for the clutch opened in introducing thehydraulic pressure into the hydraulic chamber for the clutch belongingto the clutch which is not to be connected at least in starting in therespective switching valves for the low speed clutch and the high speedclutch, is provided with a reaction force chamber on a side opposed tothe pilot chamber for the clutch constituting the switching valve forthe clutch by interposing the spool for the clutch constituting theswitching valve for the clutch, and the hydraulic pressure in thereaction force chamber for pressing the spool for the clutch to a sideof the pilot chamber for the clutch based on the hydraulic pressureintroduced to inside of the reaction force chamber is set to be large inthe running state and small in the non-running state.

Preferably, the hydraulic pressure outputted from a portioncommunicating with a delivery port of a pressurizing pump and adjustedto a predetermined pressure by a pressure control valve of an electrictype is introduced into the reaction force chamber.

Preferably, the hydraulic pressure having a reduced pressure by beingdelivered from a delivery port of a pressurizing pump and passing apressure reducing valve is introduced into the reaction force chamber bypassing a pressure control valve of an electric type or an opening andclosing valve.

Preferably, the hydraulic pressure having a reduced pressure by beingdelivered from a delivery port of pressurizing pump and passing apressure reducing valve is introduced into the reaction force chamber bypassing a valve of a hydraulic type switched based on the hydraulicpressure in the hydraulic chamber for the clutch belonging to theconnected clutch in the high speed clutch and the low speed clutch.

Preferably, the continuously variable transmission apparatus furtherincludes: a manual switching valve switched to a running mode and anon-running mode by a shift lever installed at a driver's seat; whereinalso the hydraulic pressures in the reaction chambers of the switchingvalves for the clutches opened in introducing the hydraulic pressureinto the hydraulic chambers for the clutches belonging not only to theclutch which is not to be connected in starting but also the clutchwhich is to be connected in starting in the respective switching valvesfor the low speed and the high speed clutches are increased in a stateof switching the manual switching valve to the running mode and reducedin a state of switching the manual switching valve to the non-runningmode.

Preferably, the switching valve for the high speed clutch includes areaction force chamber for the high speed clutch on a side opposed tothe pilot chamber for the high speed clutch in an axial direction byinterposing the spool for the high speed clutch, the spool for the highspeed clutch is displaced against the hydraulic pressure introduced intothe reaction force chamber for the high speed clutch by introducing thehydraulic pressure into the pilot chamber for the high speed clutch, theswitching valve for the low speed clutch includes a reaction forcechamber for the low speed clutch on a side opposed to the pilot chamberfor the low speed clutch in an axial direction by interposing the spoolfor the low speed clutch, and the spool for the low speed clutch isdisplaced against the hydraulic pressure introduced into the reactionforce chamber for the low speed clutch by introducing the hydraulicpressure into the pilot chamber for the low speed clutch.

Preferably, a pressure receiving area on a side of the pilot chamber forthe high speed clutch in the spool for the high speed clutch is widerthan a pressure receiving area on a side of the reaction force chamberfor the high speed clutch; the same hydraulic pressure is made to beable to be introduced into the hydraulic chamber for the high speedclutch and the reaction force chamber for the high speed clutch; apressure receiving area on a side of the pilot chamber for the low speedclutch in the spool for the low speed clutch is wider than a pressurereceiving area on a side of the reaction force chamber for the low speedclutch; and the same hydraulic pressure is made to be able to beintroduced into the pilot chamber for the low speed clutch and thereaction force chamber for the low speed clutch.

Preferably, the hydraulic pressure introduced into the pilot chamber forthe high speed clutch, the reaction force chamber for the high speedclutch, the pilot chamber for the low speed clutch, and the reactionforce chamber for the low speed clutch is the hydraulic pressureintroduced into the two hydraulic chambers for the high speed clutch andthe low speed clutch.

Preferably, a ratio of the pressure receiving area on the side of thereaction force chamber for the high speed clutch to the pressurereceiving area on the side of the pilot chamber for the high speedclutch as well as a ratio of the pressure receiving area on the side ofthe reaction force chamber for the low speed clutch to the pressurereceiving area on the side of the pilot chamber for the low speed clutchare both equal to or larger than 0.4 and less than 1.

Preferably, a rattle preventing spring for the high speed clutch forpressing the spool for the high speed clutch to the side of the pilotchamber for the high speed clutch is provided in the reaction forcechamber for the high speed clutch, and a rattle preventing spring forthe low speed clutch for pressing the spool for the low speed clutch tothe side of the pilot chamber for the low speed clutch is provided inthe reaction force chamber for the low speed clutch, respectively.

Preferably, a shifting manual switching valve for manually achieving afunction the same as a function of the shifting electric switching valveis provided in parallel with the shifting electric switching valve and aselecting manual switching valve for selecting either of the shiftingelectric switching valve and the shifting manual switching valve isprovided. According to any of the continuously variable transmissionapparatus of the invention constituted as described above, in switchingthe low speed mode and high speed mode, an instance of simultaneouslytransmitting power by the two clutches of the clutch for low speed andthe clutch for high speed (connecting the clutches) can be producedalthough the instance is a short period of time. Therefore, the torqueshift brought about in the toroidal type continuously valuabletransmission in switching the mode can be alleviated. That is, in thestate of transmitting power by the two clutches (the two clutches areconnected), the torque passing the toroidal type continuously variabletransmission is substantially nullified. Further, in switching the mode,the two clutches are brought into a state of transmitting power (stateof being connected) from the mode heretofore, thereafter, shifted to anew mode. Therefore, when shifting between the different modes, thetransmission ratio of the toroidal-type continuously variabletransmission is temporarily returned to a state of not being influencedby the passing torque (neutral state). The torque shift is produceddividedly in two stages between the previous mode and the neutral stateand between the neutral state and the new mode. The torque shift is notproduced abruptly between the different modes. That is, between therespective modes and the neutral state, amounts of elastically deformingrespective portions are changed based on a variation in the torque,thereby bringing about a variation in the transmission ratio of thetoroidal-type continuously variable transmission. Simultaneously, also aslip rate of a traction portion is changed. As a result, a variation inthe transmission ratio of the total of the continuously variabletransmission apparatus based on the torque shift of the toroidal-typecontinuously variable transmission is made to be gradual and the strangefeeling given to the passenger starting from the driver can bealleviated. Further, by preventing the driving system from being appliedwith an impact, durability of a constituent part of the driving systemcan be promoted.

Therefore, the invention can contribute to a realization of thecontinuously variable transmission apparatus achieving high efficiencyby combining the toroidal-type continuously variable transmission andthe planetary gear type transmission, while reducing the strange feelinggiven to the driver in switching the modes.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more readily described with reference tothe accompanying drawings:

FIG. 1 is an outline sectional view of a half portion showing an exampleof a continuously variable transmission apparatus according to theinvention.

FIG. 2 is a diagram showing a relationship between a transmission ratioof a total of the continuously variable transmission apparatus (T/M) anda transmission ratio of a toroidal-type continuously variabletransmission unit (CVU) integrated to the continuously variabletransmission apparatus.

FIG. 3 is a hydraulic circuit diagram for controlling a transmissionratio shown in Embodiment 1 of the invention.

FIG. 4 is a diagram showing a state of operating respective portions inswitching modes.

FIGS. 5A and 5B are diagrams showing two examples of changes of thehydraulic pressure in both of the chamber for a low speed clutch and thechamber for a high speed clutch.

FIG. 6 is a diagram for explaining a state of changing the transmissionratio of the total of the continuously variable transmission apparatusin accordance with a rotational speed and a torque of an engine.

FIG. 7 is a diagram showing a relationship between a passing torque anda transmission ratio with regard to the toroidal-type continuouslyvariable transmission unit and the transmission ratio of the total ofthe continuously variable transmission apparatus in a low speed mode.

FIG. 8 is a hydraulic circuit diagram substantially in correspondencewith a portion A of FIG. 3 showing Embodiment 2 of the invention.

FIG. 9 is a hydraulic circuit diagram in correspondence with a portion Aof FIG. 3 showing Embodiment 3 of the invention.

FIG. 10 is a hydraulic circuit diagram in correspondence with a portionB of FIG. 3 showing Embodiment 4 of the invention.

FIG. 11 is a diagram in correspondence with a portion C of FIG. 10showing a non-running state.

FIG. 12 is a diagram similar to FIG. 11 showing a running state.

FIG. 13 is a diagram showing movements of respective portions inswitching from a non-running state to a running state in a state ofincreasing an elastic force of a compression coil spring for a highspeed clutch.

FIG. 14 is a diagram showing movements of respective portions inswitching from the non-running state to the running state in a state ofreducing the elastic force of the same.

FIG. 15 is a diagram similar to FIG. 8 showing Embodiment 5 of theinvention.

FIG. 16 is a diagram similar to FIG. 8 showing Embodiment 6 of theinvention.

FIG. 17 is a diagram similar to FIG. 8 showing Embodiment 7 of theinvention in a low speed mode.

FIG. 18 is a diagram similar to FIG. 17 in a high speed mode.

FIG. 19 is a diagram similar to FIG. 17 in an untraveling mode.

FIG. 20 is a diagram similar to FIG. 9 showing Embodiment 8 of theinvention.

FIG. 21 is a diagram similar to FIG. 9 showing Embodiment 9 of the same.

FIG. 22 is a diagram in correspondence with a portion F of FIG. 20showing Embodiment 10 of the invention.

FIG. 23 is a hydraulic circuit diagram in correspondence with a portionA of FIG. 3 showing Embodiment 3 of the invention.

FIGS. 24A and 24B are diagrams showing pressure of each portion whenswitching the clutch.

FIGS. 25A-25C are diagrams showing pressure of each portion whenswitching the clutch in Embodiment 1.

FIG. 26 is a diagram similar to FIG. 23 showing Embodiment 13 of theinvention.

FIG. 27 is a sectional view showing an example of a toroidal-typecontinuously variable transmission known in a prior art.

FIG. 28 is a sectional view taken along a line D-D of FIG. 27.

FIG. 29 is a sectional view taken along a line E-E of FIG. 16.

FIG. 30 is an outline sectional view showing a first example of acontinuously variable transmission apparatus known in a related art.

FIG. 31 is an outline sectional view showing a second example of thesame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In embodying the invention, for example, starting to transmit power byone clutch (hydraulic type, electromagnetic type, dry friction clutch)is detected by displacement (stroke) of a driving member (a piston inthe case of hydraulic type) for connecting the clutch. The detection bythe displacement (stroke) is carried out by a displacement meter of apotentiometer or the like installed at the driving member (piston) or aportion displacing along with the drive member (piston).

Or, the clutch for low speed is connected by introducing hydraulicpressure into a hydraulic chamber for the low speed clutch and theclutch for high speed is connected by introducing hydraulic pressureinto a hydraulic chamber for the high speed clutch. Further, starting totransmit power to one clutch of the clutch for low speed and the clutchfor high-speed is detected by hydraulic pressure in the hydraulicchamber for the clutch for introducing hydraulic pressure when theclutch is connected. Detection of the hydraulic pressure may be carriedout mechanically by a hydraulic part for displacing a member byrectified pressure such as a spool valve or the like, or may be carriedout electrically by a pressure meter.

That is, detection of hydraulic pressure in the hydraulic chamber forthe clutch is electrically carried out by a pressure sensor. Or, thereis provided a switching valve switched in accordance with introductionof hydraulic pressure into the hydraulic chamber for the clutch in orderto mechanically detect hydraulic pressure in the hydraulic chamber forthe clutch. A spool constituting the switching valve is displaced alongwith introduction of hydraulic pressure into the hydraulic chamber forthe clutch. Further, based on displacement of the spool, hydraulicpressure introduced into the hydraulic chamber for the clutch of otherclutch is reduced.

When constituted in this way, starting to operate to connect one clutchis firmly detected by a simple structure, in switching the low speedmode and high speed mode, an instance of transmitting power by the twoclutches for low speed and high speed (the two clutches are connected)can firmly be produced and the torque shift brought about in thetoroidal type continuously variable transmission in switching the modecan be alleviated.

Further, in embodying the invention as described above, preferably, astate of introducing hydraulic pressure into the hydraulic chamber forthe low speed clutch is controlled by the switching valve for the lowspeed clutch having a spool for the low speed clutch displaced inaccordance with introduction of hydraulic pressure into a pilot chamberfor the low speed clutch. Further, a state of introducing hydraulicpressure into the hydraulic chamber for the high speed clutch iscontrolled by the switching valve for the high speed clutch having aspool for the high speed clutch displaced in accordance withintroduction of hydraulic pressure into a pilot chamber for the highspeed clutch. Further, a state of introducing hydraulic pressure intothe hydraulic chamber for the low speed clutch and a state ofintroducing hydraulic pressure into the pilot chamber for the high speedclutch are controlled by a switching valve for shifting having a spoolfor switching displaced in accordance with introduction of hydraulicpressure into the pilot chamber for switching. Further, a state ofintroducing hydraulic pressure into the pilot chamber for switching iscontrolled by an electric switching valve for shifting. Further, theswitching valve for the low speed clutch reduces hydraulic pressureintroduced into the hydraulic chamber for the low speed clutch inaccordance with introduction of hydraulic pressure into the pilotchamber for the low speed clutch and the hydraulic pressure introducedinto the pilot chamber for the low speed clutch is made to constitutehydraulic pressure introduced into the hydraulic chamber for the highspeed clutch. Further, the switching valve for the high speed clutchreduces hydraulic pressure introduced into the hydraulic chamber for thehigh speed clutch in accordance with introduction of hydraulic pressureinto the pilot chamber for the high speed clutch and hydraulic pressureintroduced into the pilot chamber for the high speed clutch is made toconstitute hydraulic pressure introduced into the hydraulic chamber forthe low speed clutch.

When constituted in this way, by only switching a single piece of anelectromagnetic valve for shifting, thereafter, it is mechanicallydetected that operation of connecting one clutch is started based onswitching of the switching valve of the hydraulic type (displacement ofthe spool in accordance with introduction of hydraulic pressure into thepilot chamber of the spool valve) and in switching the low speed modeand high speed mode, an instance of transmitting power by the twoclutches for low speed and for high speed (two clutches are connected)can firmly be produced.

In embodying the invention, for example, there is used the switchingvalve for the high speed clutch having an elastic member for the highspeed clutch on a side opposed to the pilot chamber for the high speedclutch in the axial direction by interposing the spool for the highspeed clutch, wherein the spool for the high speed clutch is displacedagainst an elastic force of the elastic member for the high speed clutchin accordance with introduction of hydraulic pressure into the pilotchamber for the high speed clutch.

Further, there is used the switching valve for the low speed clutchhaving an elastic member for the low speed clutch on a side opposed tothe pilot chamber for the low speed clutch in the axial direction byinterposing the spool for the low speed clutch, wherein the spool forthe low speed clutch is displaced against an elastic force of theelastic member for the low speed clutch in accordance with introductionof hydraulic pressure into the pilot chamber for the low speed clutch.

Further, in embodying the invention having the above-describedconstitution, preferably, the elastic force of the elastic member forthe clutch for elastically pressing the spool for clutch, which isintegrated to one of the switch valves for the low speed clutch and forthe high speed clutch, opened in introducing the hydraulic pressure intothe hydraulic chamber for the clutch, which belongs to the clutch (forhigh speed) that should not be connected in starting a vehicle, is setto be large in a running state and small in a non-running state.

Therefore, preferably, the elastic member for the clutch is constitutedby a compression coil spring for the clutch. Further, the compressioncoil spring for the clutch is provided between the spool for the clutchand the pressing piston displaceably provided in the axial direction atinside of the cylinder provided at a position opposed to the pilotchamber for the clutch in the axial direction by interposing the spoolfor the clutch. Further, when the running state is selected, thepressing piston is displaced to the side of the spool for the clutch bythe hydraulic pressure introduced into the cylinder portion to increasethe elastic force of the compression coil spring for the clutch. Incontrast thereto, when the hydraulic pressure in the cylinder portion isexcluded by selecting the non-running state, the pressing piston isdisplaced to a side of being remote from the spool for the clutch toreduce the elastic force for the compression coil spring for the clutch.

When constituted in this way, in switching the low speed mode and thehigh speed mode in the running state, the moment in which the bothclutches of the low speed clutch and the high speed clutch are connectedcan firmly be produced and when the running state is selected from thenon-running state, the clutch which should not be connected under thestate can be prevented from being connected although the moment is ashort period of time.

Further, in embodying the invention, preferably, there is provided amanual switching valve capable of switching a running mode (runningstate) and a nonrunning mode (nonrunning state) by a shift leverinstalled at a driver's seat. Further, not only with regard to anelastic force of an elastic member for a clutch of a clutch which is notto be connected in starting in the switch valves of the respective lowspeed and high speed clutches but also with regard to an elastic forceof an elastic member for the clutch integrated to the switching valvefor the clutch opened in introducing hydraulic pressure into thehydraulic pressure chamber for the clutch belonging to the clutch to beconnected in starting, the elastic force is increased in a state ofswitching the manual switching valve to the running mode and reduced ina state of switching the manual switching valve to the nonrunning mode.

When constituted in this way, in running at high speed (although notpreferable), a driver selects the nonrunning mode {neutral (N) range}for operational failure or running by inertia and thereafter returns thestate to the running mode {drive (D) range} while staying in the highspeed running state, the clutch (clutch for low speed) not to beconnected under the state can be prevented from being connected althoughthe time period is short.

In this case, preferably, a signal indicating a vehicle speed isinputted to a controller, the controller connects one clutch of theclutch for low speed and the clutch for high speed in accordance withthe vehicle speed at a time point of switching from the nonrunning modeto the running mode, that is, the clutch for high speed in running at ahigh speed (for example, a case equal to or faster than 30 km/h) and theclutch for low speed in running at low speed (for example, a case ofless than 30 km/h). The other clutch is made to stay in an unconnectedstate.

Further, in embodying the invention, preferably, there is used theswitching valve for the clutch opened in introducing hydraulic pressureinto the hydraulic chamber for the clutch belonging to the clutch not tobe connected at least in starting having a reaction force chamber. Thereaction chamber is integrated to a side opposed to the pilot chamberfor the clutch constituting the switching valve for the clutch in theaxial direction by interposing the spool for the clutch constituting theswitching valve for the clutch. Further, hydraulic pressure in thereaction force chamber for pressing the spool for the clutch to a sideof the pilot chamber for the clutch based on hydraulic pressureintroduced to inside thereof is set to be large in the running state andsmall in the nonrunning state.

In this case, for example, hydraulic pressure outputted from a portioncommunicating with a delivery port of a pressurizing pump and controlledto a predetermined pressure by a pressure control valve of an electrictype is introduced into the reaction force chamber.

Or, hydraulic pressure reduced by passing a pressure reducing valveafter having been delivered from the delivery port of the pressurizingpump is introduced into the reaction force chamber by passing thepressure control valve of the electric type or an opening/closing valve.

Or, hydraulic pressure reduced by passing a pressure reducing valveafter having been delivered from the delivery port of the pressurizingpump is introduced into the reaction force chamber by passing a valve ofa hydraulic type switched based on the pressure in the hydraulic chamberfor the clutch belonging to the clutch connected in the clutch for highspeed and the clutch for low speed.

Also by constituting in this way, in switching the low speed mode andthe high speed mode in running, the instance of connecting the twoclutches of the clutch for the low speed and the clutch for the highspeed can firmly be produced and when the running state is selected fromthe nonrunning state, the clutch which is not to be connected under thestate can be prevented from being connected although a time period isshort.

Further, in embodying the invention, preferably, there is provided amanual switching valve switched to the running mode (running state) andthe non running mode (nonrunning state) by the shift lever installed atthe driver's seat. Further, not only with regard to hydraulic pressureof the clutch which is not to be connected in starting in the switchingvalves of the respective low speed and high speed clutches, but alsowith regard to hydraulic pressure in the reaction force chamber of theswitching valve for the clutch opened in introducing hydraulic pressureinto the hydraulic chamber for the clutch belonging to the clutch to beconnected in starting, the hydraulic pressure is increased in the stateof switching the manual switching valve to the running mode and reducedin the state of switching the manual switching valve to the nonrunningstate.

When constituted in this way, in running at high speed, when the driverselects the nonrunning state and thereafter returns the state to therunning state while staying in the high speed running state, the clutch(clutch for low speed) which is not to be connected under the state canbe prevented from being connected although the time period is short.

Also in this case, preferably, a signal indicating the vehicle speed isinputted to the controller, one clutch of the clutch for low speed andthe clutch for high speed is connected in accordance with a vehiclespeed at a time point of switching from the nonrunning mode to therunning mode and other clutch is made to stay in the unconnected state.

Further, in embodying the invention, for example, there is used theswitching valve for the high speed clutch having the reaction forcechamber for the high speed clutch on the side opposed to the pilotchamber for the high speed clutch in the axial direction by interposingthe spool for the high speed clutch, wherein the spool for the highspeed clutch is displaced against hydraulic pressure introduced into thereaction chamber for the high speed clutch in accordance withintroduction of hydraulic pressure into the pilot chamber for the highspeed clutch.

Further, there is used the switching valve for the low speed clutchhaving the reaction chamber for the low speed clutch on the side opposedto the pilot chamber for the low speed clutch in the axial direction byinterposing the spool for the low speed clutch, wherein the spool forthe low speed clutch is displaced against hydraulic pressure introducedinto the reaction force chamber for the low speed clutch in accordancewith introduction of hydraulic pressure into the pilot chamber for thelow speed clutch.

Further, in embodying the invention, preferably, a pressure receivingarea on a side of the pilot chamber for the high speed clutch is made tobe wider than a pressure receiving area on a side of the reaction forcechamber for the high speed clutch in the spool for the high speed clutchand the same hydraulic pressure is made to be able to introduce into thepilot chamber for the high speed clutch and the reaction force chamberfor the high speed clutch.

Further, a pressure receiving area on a side of the pilot chamber forthe low speed clutch is made to be wider than a pressure receiving areaon a side of the reaction chamber for the low speed clutch in the spoolfor the low speed clutch and the same hydraulic pressure is made to beable to introduce into the pilot chamber for the low speed clutch andthe reaction force chamber for the high speed clutch.

When constituted in this way, regardless of a variation in hydraulicpressure, the switching valve for the high speed clutch and theswitching valve for the low speed clutch can firmly be switched.

In embodying the invention, for example, hydraulic pressures introducedinto the pilot chamber for the high speed clutch, the reaction forcechamber for the high speed clutch, the pilot chamber for the low speedclutch and the reaction force chamber for the low speed clutch are madeto be hydraulic pressures introduced into the two hydraulic chambers forthe high speed clutch and the low speed clutch.

Further, preferably, a ratio of the pressure receiving area on the sideof the reaction force chamber for the high speed clutch to the pressurereceiving area on the side of the pilot chamber for the high speedclutch as well as a ratio of the pressure receiving area on the side ofthe reaction force chamber for the low speed clutch and the pressurereceiving area on the side of the pilot chamber for the low speed clutchare both set to be equal to or larger than 0.4 and less than 1.

Further, preferably, there is provided a rattle preventing spring forthe high speed clutch for pressing the spool for the high speed clutchto the side of the pilot chamber for the high speed clutch in thereaction force chamber for the high speed clutch. Further, there isprovided a rattle preventing spring for the low speed clutch forpressing the spool for the low speed clutch to the side of the pilotchamber for the low speed clutch in the reaction force chamber for thelow speed clutch.

Further, in embodying the invention, preferably, the switching valve forthe low speed clutch reduces hydraulic pressure introduced into thehydraulic chamber for the low speed clutch in accordance withintroduction of hydraulic pressure into the pilot chamber for the lowspeed clutch and constitutes hydraulic pressure introduced into thepilot chamber for the low speed clutch to be hydraulic pressureintroduced into the hydraulic chamber for the high speed clutch.Further, the switching valve for the high speed clutch reduces hydraulicpressure introduced into the hydraulic chamber for the high speed clutchin accordance with introduction of hydraulic pressure into the pilotchamber for the high speed clutch and constitutes hydraulic pressureintroduced into the pilot chamber for the high speed clutch to behydraulic pressure introduced into the hydraulic chamber for the lowspeed clutch.

When constituted in this way, by switching a single piece of theelectric switching valve for shifting, thereafter, based on a delay timeperiod of switching the valve of the hydraulic type, a time period ofsimultaneously transmitting the power by the two clutches can beproduced for a short period of time. Therefore, a structure facilitatingcontrol and difficult to be failed can be realized at low cost.

Further, in embodying the invention, preferably, there is provided firstresisting means constituting a resistance against passing pressurizedoil and retarding pressure rise in the pilot chamber for the low speedclutch in comparison with pressure rise in the hydraulic chamber for thehigh speed clutch in the midst of a first pressure introducing path forintroducing hydraulic pressure introduced into the hydraulic chamber forthe high speed clutch into the pilot chamber for the low speed clutch.Further, there is provided second resisting means for constituting aresistance against passing pressurized oil and retarding pressure risein the pilot chamber for the high speed clutch in comparison withpressure rise in the hydraulic chamber for the low speed clutch in themidst of a second hydraulic pressure introducing path for introducinghydraulic pressure introduced into the hydraulic chamber for the lowspeed clutch into the hydraulic chamber for the high speed clutch.

When constituted in this way, a delay time period of switching the valveof the hydraulic type is ensured and the time period of simultaneouslytransmitting the power by the two clutches for low speed and high speedcan firmly be produced.

Further, in the case of embodying the invention having theabove-described constitution, preferably, at a middle of the hydraulicpressure discharging path on the side of the low speed clutch, there isprovided a throat on the side of the low speed clutch constituting aresistance against flow of the pressurized oil passing the hydraulicpressure discharge path on the side of the low speed clutch. Further, ata middle of the hydraulic pressure discharge path on the side of thehigh speed clutch, there is provided a throat on the side of the highspeed clutch constituting a resistance against flow of the pressurizedoil passing the hydraulic pressure discharging path on the side of thehigh speed clutch.

When constituted in this way, the time period required for switching thetwo clutches from the connected state to the non-connected state can beincreased and a short time period of the time period of simultaneouslytransmitting the power by the both clutches can be produced by a simplestructure.

Further, in the case of embodying the invention having theabove-described constitution, further preferably, a single hydraulicpressure discharge path is constituted by merging a downstream portionof the hydraulic pressure discharge path on the side of the low speedclutch and a downstream portion of the hydraulic pressure discharge pathon the side of the high speed clutch. Further, a single throat providedat a portion of the single hydraulic pressure discharge path is providedwith both of a function as the throat on the side of the low speedclutch and a function as the throat on the side of the high speedclutch.

When constituted in this way, the constitution for producing a shorttime period of the time period of simultaneously transmitting the powerby the both clutches can further be simplified by prolonging the timeperiod required for switching the both clutches from the connected stateto the non-connected state.

Further, in the case of embodying the invention, preferably, at aportion constituting the single low pressure side hydraulic path bymerging the pressure introducing path on the side of the low speedclutch and the pressure discharging path on the side of the low speedclutch at a vicinity of the hydraulic chamber for the low speed clutch,there are provided a check valve on the side of the low speed clutchopened in introducing the hydraulic pressure into the hydraulic chamberfor the low speed clutch and closed in discharging the hydraulicpressure from inside of the hydraulic chamber for the low speed clutchand a throat on the side of the low speed clutch in parallel with eachother. Further, at a portion of constituting the single high pressureside hydraulic pressure path by merging the pressure introducing path onthe side of the high speed clutch and the pressure discharging path onthe side of the high speed clutch at a vicinity of the hydraulic chamberfor the high speed clutch, there are provided a check valve on the sideof the high speed clutch opened in introducing the hydraulic pressureinto the hydraulic chamber for the high speed clutch and closed indischarging the hydraulic pressure from inside of the hydraulic chamberfor the high speed clutch and the throat on the side of the high speedclutch in parallel with each other.

Even by constituting in this way, a short time period of the time periodof simultaneously transmitting the power by the both clutches can beproduced by prolonging the time period required for switching the bothclutches from the connected state to the non-connected state by a simplestructure.

Further, in the case of embodying the invention, preferably, at a middleof the hydraulic pressure discharging path on the side of the low speedclutch, there is provided an electric valve on the side of the speedclutch of an electromagnetic valve or the like for cutting flow of thepressurized oil passing the hydraulic pressure discharging path on theside of the low speed clutch by a desired time period. Further, at amiddle of the hydraulic pressure discharging path on the side of thehigh pressure clutch, there is provided an electric valve on the side ofthe high speed clutch of an electric magnetic valve or the like forcutting flow of the pressurized oil passing the hydraulic pressuredischarging path on the side of the high speed clutch by a desired timeperiod.

Even by constituting in this way, the short time period of the timeperiod of simultaneously transmitting the power by the both clutches canbe produced by prolonging the time period required for switching theboth clutches from the connected state to the non-connected state by asimple structure.

In the case of embodying the invention having such a constitution,preferably, a single hydraulic pressure discharging path is constitutedby merging a downstream portion of the hydraulic pressure dischargingpath on the side of the low speed clutch and a downstream portion of thehydraulic pressure discharging path on the side of the high speedclutch. Further, a single electric valve of an electric magnetic valveor the like provided at a portion of the single hydraulic pressuredischarging path is provided with both of a function as an electricvalve on the side of the low speed clutch and an electric valve on theside of the high speed clutch.

When constituted in this way, the constitution for producing the shorttime period of the time period of simultaneously transmitting the powerby the both clutches can further be simplified by prolonging the timeperiod required for switching the both clutches from the connected tothe non-connected state.

Further, in the case of embodying the invention, preferably, theinvention is used as a transmission for a vehicle and a time period inwhich an electric valve of an electromagnetic valve or the like cutsflow of the pressurized oil passing the hydraulic pressure dischargingpath can be controlled in accordance with a situation of running thevehicle.

In this case, as the situation of running the vehicle utilized forcontrolling to open and close the electric valve, there are conceivableone kind or two or more kinds selected from a vehicle speed, anaccelerator opening degree, an acceleration degree, a decelerationdegree, the torque passing the toroidal-type continuously variabletransmission and the like.

When the time period of cutting of the pressurized oil passing thehydraulic pressure discharging path by the electric valve is controlledin accordance with the situation of running the vehicle, the impactproduced in changing the speed can further be alleviated by furtherfinely connecting and disconnecting the both clutches.

Further preferably, there is provided a shifting manual switch valveachieving a function the same as that of the shifting electric switchvalve manually in parallel with the shifting electric switch valve andthere is provided a selecting manual switch valve for selecting eitherof the shifting electric switch valve and the shifting manual switchvalve.

When constituted in this way, in failing the shifting electric switchvalve, it is also possible to ensure a minimum running function which isneeded in bringing the vehicle to a repair shop by running the vehicleby itself by enabling to change the low speed mode and the high speedmode manually.

Embodiment 1

FIGS. 1 through 6 show Embodiment 1 of the invention. The embodimentshows a case of applying the invention to a continuously variabletransmission apparatus of a geared neutral type. Further, in addition toa function of restraining an abrupt variation in a transmission ratiobased on a torque shift in switching modes, there is effectively carriedout a control of controlling a torque applied to an output shaft to adesired value when a transmission ratio of a total of the continuouslyvariable transmission apparatus is extremely increased in order to stopthe output shaft while rotating an input shaft. Further, although thecontinuously variable transmission apparatus shown in FIG. 1 is providedwith a function similar to that of the above-described continuouslyvariable transmission apparatus known in the prior art shown in FIG. 29,performance of integrating a portion of the planetary gear typetransmission 25 b is promoted by devising a structure of the portion ofthe planetary gear type transmission 25 b.

Respective pairs of planetary gear elements 52 a, 52 b, 53 a, 53 b arerotatably supported by both side faces of a carrier 26 a rotated alongwith the input shaft 1 and the pair of input side disks 2, 2. Among therespective planetary gear elements 52 a, 52 b, 53 a, 53 b, the planetarygear elements 52 a, 52 b and 53 a, 53 b constituting the pairs arebrought in mesh with each other, the planetary gear elements 52 a, 53 aon an inner diameter side are brought in mesh with a first and a secondsun gear 55, 56 fixedly provided to a hollow rotating shaft 31 a coupledto the output side disk 5 a and a transmitting shaft 54 and planetarygear elements 52 a, 53 b on an outer diameter side are brought in meshwith a ring gear 34 a, respectively. Further, the hollow rotating shaft31 and the transmitting shaft 54 are supported to be able to rotateindependently from each other and concentrically with input shaft 1.

Meanwhile, planetary gear elements 59 a, 59 b are rotatably supported bya second carrier 58 provided at a surrounding of a third sun gear 57fixedly connected to other end portion (right end portion of FIG. 1) ofthe transmitting shaft 54. Further, the second carrier 58 is fixedlyprovided to a base end portion (left end portion of FIG. 1) of an outputshaft 37 b arranged concentrically with an input shaft 1. Further, therespective planetary gear elements 59 a, 59 b are brought in mesh witheach other, the planetary gear element 59 a on an inner diameter side isbrought in mesh with the third sun gear 57 and the planetary gearelement 59 b on an outer diameter side is brought in mesh with a secondring gear 38 a provided rotatably at a surrounding of the second carrier58, respectively. Further, the ring gear 34 a and the second carrier 58are made to be engageable and disengageable to and from each other by alow speed clutch 39 b and the second ring gear 38 a and a fixed portionof a housing or the like are made to be engageable and disengageable toand from each other by a high speed clutch 40 b.

In the case of the continuously variable transmission apparatusconstituted in this way, in a state of connecting the low speed clutch39 b and disconnecting the high speed clutch 40 b, power of the inputshaft 1 is transmitted to the output shaft 37 b via the ring gear 34 a.Further, by changing a transmission ratio of the toroidal-typecontinuously variable transmission 24, a transmission ratio e_(CVT) of atotal of the continuously variable transmission apparatus, that is, aspeed ratio between the input shaft 1 and the output shaft 37 b ischanged. A relationship between a transmission ratio e_(CVU) of thetoroidal-type continuously variable transmission 24 and the transmissionratio e_(CVT) of the total of the continuously variable transmission atthis occasion is represented by Equation (1) shown below when a ratio ofa teeth number m₃₄ of the ring gear 34 a to a teeth number m₅₅ of thefirst sun gear 55 is designated by notation i₁ (=m₃₄/m₅₅).e _(CVT)=(e _(CVU) +i ₁−1)/i ₁  (1)

Further, when the ratio i₁ of the teeth numbers is, for example, 2, therelationship of the two transmission ratios e_(CVU), e_(CVT) is changedas shown by a line segment α of FIG. 2.

In contrast thereto, in a state of disconnecting the low speed clutch 39b and connecting the high speed clutch 40 b, power of the input shaft 1is transmitted to the output shaft 37 b via the respective planetarygear elements 52 a, 52 b, the ring gear 34 a, the respective planetarygear elements 53 a, 53 b, the transmitting shaft 54, the respectiveplanetary gear elements 59 a, 59 b, and the second carrier 58. Further,by changing the transmission ratio e_(CVU) of the toroidal-typecontinuously variable transmission 24, the transmission ratio e_(CVT) ofthe total of the continuously variable transmission apparatus ischanged. A relationship between the transmission ratio e_(CVU) of thetoroidal-type continuously variable transmission 24 and the transmissionratio e_(CVT) of the total of the continuously variable transmissionapparatus at this occasion is as represented by Equation (2) shownbelow. Further, in Equation (2), notation i₁ designates the ratio(m₃₄/m₅₅) of the teeth number m₃₄ of the ring gear 34 a to the teethnumber m₅₅ of the first sun gear 55, notation i₂ designates a ratio(m₃₄/m₅₆) of the teeth number m₃₄ of the ring gear 34 a to the teethnumber m₅₆ of the second sun gear 56, and notation i₃ designates a ratio(m₃₈/m₅₇) of a teeth number m₃₈ of the second ring gear 38 a to theteeth number m₅₇ of the third sun gear 57, respectively.e _(CVT)={1/(1−i ₃)}·{1+(i ₂ /i ₁)(e _(CVU)−1)}  (2)

Further, a relationship between the two transmission ratios e_(CVU),e_(CVT) when i₁=2, i₂=2.2 and i₃=2.8 in the respective ratios is changedas shown by a line segment β of FIG. 2.

In operating the continuously variable transmission apparatusconstituted and operated as described above, at a portion of connectingthe line segments α, β shown in FIG. 2, the low speed mode and the highspeed mode are switched based on connection and disconnection of the lowspeed clutch 39 b and the high speed clutch 40 b. Further, based on theswitching, as described above, a direction and a magnitude of the torquepassing the toroidal-type continuously variable transmission 24 arechanged. Hence, by a hydraulic circuit as shown by FIG. 3, in changingthe modes, a time period of connecting both clutches of the low speedclutch 39 e and the high speed clutch 40 b is set by a short timeperiod.

For that purpose, in the case of the embodiment, there is used the lowspeed clutch 39 a of a wet multiplate type connected by introducing ahydraulic pressure into a hydraulic chamber 60 for the low speed clutch.Further, there is used the high speed clutch 40 b of a wet multiplatetype connected by introducing a hydraulic pressure into a hydraulicchamber 61 for the high speed clutch. Further, a hydraulic pressurebased on a pressurized oil sucked from an oil storage 62 (oil panprovided at a bottom portion of the continuously variable transmissionapparatus), delivered from a pressurizing pump 63 and controlled to apredetermined pressure by a pressure reducing valve 65 to apredetermined pressure after passing a manual switch valve 64 isintroduced to either or both of the hydraulic chamber 60 for the lowspeed clutch and the hydraulic chamber 61 for the high speed clutch.

First, a state of introducing the hydraulic pressure into the hydraulicchamber 60 for the low speed clutch is switched by a switch vale 66 forthe low speed clutch. The switch valve 66 for the low speed clutchcommunicates the hydraulic chamber 60 for the low speed clutch to eitherof the oil storage 62 and a delivery port of the pressure reducing valve65 in accordance with a displacement in an axial direction of a spool 67for the low speed clutch. Further, in order to displace the spool 67 forthe low speed clutch in the axial direction, one end (right end of FIG.3) in the axial direction of the spool 67 for the low speed clutch isprovided with a compression coil spring 68 for the low speed clutchconstituting an elastic member for the low speed clutch and other end(left end of FIG. 3) in the axial direction is provided with a pilotchamber 69 for the low speed clutch, respectively.

According to the switch valve 66 for the low speed clutch, in a state ofstopping to introduce the hydraulic pressure into the pilot chamber 69for the low speed clutch (open to the oil storage 62), the spool 67 forthe low speed clutch is displaced to a state shown in FIG. 3 base on anelastic force of the compression coil spring 68 for the low speed clutchto introduce the hydraulic pressure into the hydraulic chamber 60 forthe low speed clutch. Under the state, the low speed clutch 39 b isbrought into a connected state. In contrast thereto, in a state ofintroducing the hydraulic pressure into the pilot chamber 69 for the lowspeed clutch, the spool 67 for the low speed clutch is displaced to aside reverse to that of the state shown in FIG. 3 against the elasticforce of the compression coil spring 68 for the low speed clutch tocommunicate the hydraulic chamber 60 for the low speed clutch to the oilstorage 62. Under the state, the low speed clutch 39 b is brought into anon-connected state.

Further, a state of introducing the hydraulic pressure into thehydraulic chamber 61 for the high speed clutch is switched by a switchvalve 70 for the high speed clutch. The switch valve 70 for the highspeed clutch communicates the hydraulic chamber 61 for the high speedclutch to either of the delivery port of the pressure reducing valve 65and the oil storage 62 in accordance with a displacement in an axialdirection of a spool 71 for the high speed clutch. Further, in order todisplace the spool 71 for the high speed clutch in the axial direction,a side of one end (left end of FIG. 3) in the axial direction of thespool 71 for the high speed clutch is provided with a compression coilspring 72 for the high speed clutch constituting an elastic member forthe high speed clutch and a side of other end (right end of FIG. 3) inthe axial direction is provided with a pilot chamber 73 for the highspeed clutch, respectively.

According to the switch valve 70 for the high-speed clutch, in a stateof stopping to introduce the hydraulic pressure into the pilot chamber73 of the high speed clutch, the spool 71 for the high speed clutch isdisplaced to a side reverse to a state shown in FIG. 3 based on anelastic force of the compression coil spring 72 for the high speedclutch to introduce the hydraulic pressure into the hydraulic chamber 61for the high speed clutch. Under the state, the high speed clutch 40 bis brought into a connected state. In contrast thereto, in a state ofintroducing the hydraulic pressure into the pilot chamber 73 for thehigh speed clutch, the spool 71 for the high speed clutch is displacedin the state shown in FIG. 3 against the elastic force of thecompression coil spring 72 for the high speed clutch to communicate thehydraulic chamber 61 for the high speed clutch to the oil storage 62.Under the state, the high speed clutch 40 b is brought into anon-connected state.

Further, a state of introducing the hydraulic pressure to the pilotchamber 60 for the low speed clutch of the switch valve 66 for the lowspeed clutch and the pilot chamber 73 for the high speed clutch of theswitch valve 70 for the high speed clutch is controlled by a shiftingswitch valve 74. The shifting switch valve 74 introduces the hydraulicpressure to either one of the pilot chamber 69 for the low speed clutchand the pilot chamber 73 for the high speed clutch and simultaneouslycommunicates other thereof to the oil storage 62 in accordance withdisplacement in an axial direction of a switching spool 75. In order todisplace the switching spool 75 in the axial direction, a side of oneend (left end of FIG. 3) of the switching spool 75 is provided with aswitching pilot chamber 76 and other end side thereof is provided with aswitching compression coil spring 77 constituting a switching elasticmember, respectively. The shifting switch valve 74 is switched to astate shown in FIG. 3 when the pressurized oil is introduced into theswitching pilot chamber 76 to communicate the pilot chamber 69 for thelow speed clutch to the oil storage 62 to simultaneously introduces thehydraulic pressure delivered from the switch valve 66 for the low speedclutch to the hydraulic chamber 60 for the low speed clutch to the pilotchamber 73 for the high speed clutch. In contrast thereto, in a state inwhich the pressurized oil is not introduced to the switching pilotchamber 76 (in which the switching pilot chamber 76 is communicated withthe oil storage 62), the state is switched to a side reverse to thestate shown in FIG. 3, the pilot chamber 73 for the high speed clutch iscommunicated to the oil storage 62 and simultaneously, the hydraulicpressure delivered from the switch valve 70 for the high speed clutch tothe hydraulic chamber 61 for the high speed clutch is introduced to thehydraulic chamber 69 for the low speed clutch.

Further, a state of introducing the hydraulic pressure to the switchingpilot chamber 76 is controlled by an electromagnetic switch valve 78constituting a shifting electric switch valve. The electromagneticswitch valve 78 is switched to a state of communicating the switchingpilot chamber 76 to a delivery port of the second pressurizing pump 79and a state of communicating to the oil storage 62 by displacing thespool based on electricity conduction to a solenoid. That is, theelectromagnetic switch valve 78 displaces the spool to a state shown inFIG. 3 based on an elastic force of the spring to introduce a hydraulicpressure based on a pressurized oil delivered from the delivery port ofthe second pressurizing pump 79 to the switching pilot chamber 76 whenelectricity is not conducted to the solenoid. In contrast thereto, whenelectricity is conducted to the solenoid, the spool is displaced to aside reverse to the state shown in FIG. 3 against the elastic force ofthe spring to communicate the switching pilot chamber 76 to the oilstorage 62.

In the case of the embodiment, the torque shift brought about at thetoroidal-type continuously variable transmission 24 is alleviated inswitching the modes by producing a moment of connecting both clutches ofthe low speed clutch 39 b and the high speed clutch 40 b in switchingthe low speed mode and the high speed mode by the above-describedhydraulic circuit. An explanation will be given as follows of the reasonof capable of alleviating the torque shift while explaining operation ofshifting from the low speed mode to the high speed mode in reference toFIG. 4 and FIG. 5 in addition to FIG. 3.

In the low speed mode, as shown by left end portions of bold lines a, bof FIG. 4 and a bold line α and a dashed line β in FIG. 5B, thehydraulic pressure in the hydraulic chamber for the low speed clutch ishigh and the hydraulic pressure in the hydraulic chamber 61 for the highspeed clutch is low. Under the state, the spool 67 for the low speedclutch constituting the switch valve 66 for the low speed clutch ispresent on the left side of FIG. 3 as shown by a left end portion of abold line c of FIG. 4 and the spool 71 for the high speed clutchconstituting the switch valve 70 for the high speed clutch is present onthe left side of FIG. 3 as shown by a left end portion of the bold lined of FIG. 4, respectively. Further, electricity conduction to theelectromagnetic switch valve 78 is stopped (OFF) as shown by a left endportion of a bold line e of FIG. 4 and the switching spool 75constituting the shifting switch valve 74 is present on the light sideof the FIG. 3 as shown by a left end portion of a bold line f of FIG. 4.

When a speed of running a vehicle mounted with a continuously variabletransmission apparatus is increased, a controller, not illustrated,determines to shift from the low speed mode to the high speed mode andstarts conducting electricity to the electromagnetic switch valve 78 asshown by a middle portion of the bold line e of FIG. 4. As a result, thespool of the electromagnetic switch valve 78 is displaced, the switchingpilot chamber 76 of the shifting switch valve 74 communicates with theoil storage 62, and the switching spool 75 constituting the shiftingswitch valve 74 is displaced from right to left of FIG. 3 as shown by amiddle portion of the bold line f. Further, prior to starting to conductelectricity to the electromagnetic switch valve 78, the controllersubstantially nullifies (stops) a rotating speed of the second ring gear38 a by controlling the transmission ratio of the toroidal-typecontinuously variable transmission 24.

As a result of the displacement of the switching spool 75 from the rightside to the left side in FIG. 3, the pilot chamber 73 for the high speedclutch of the switch valve 70 for the high speed clutch is released tothe oil storage 62, the spool 71 for the high speed clutch is pressed bythe compression coil spring 72 for the high speed clutch and displacedto the right side of FIG. 3 as shown by a middle portion of the boldline d of FIG. 4. Further, the hydraulic pressure is introduced into thehydraulic chamber 61 for the high speed clutch via the switch valve 70for the high speed clutch. The hydraulic pressure in the hydraulicchamber 61 for the high speed clutch is increased while narrowingclearances present among a plurality of sheets of clutch platesconstituting the high speed clutch 40 b and therefore, a time period tosome degree is required in increasing the hydraulic pressure in thehydraulic chamber 61 for the high speed clutch as shown by middleportions of the bold line b of FIG. 4 and the bold line a in FIG. 5B.Further, switching of the switch valve 66 for the low speed clutch basedon introduction of the hydraulic pressure the same as that of thehydraulic chamber 61 for the high speed clutch is retarded.

That is, during some period of time after starting to introduce thehydraulic pressure into the hydraulic chamber 61 for the high speedclutch, energy of the hydraulic pressure is consumed for displacing thepiston for narrowing the clearances among the respective clutch platesand sufficient energy is not supplied to the pilot chamber 69 for thelow speed clutch of the switch valve 66 for the low speed clutch. Thespool 67 for the low speed clutch constituting the switch valve 66 forthe low speed clutch starts displacing to the right of FIG. 3 after thehydraulic pressure in the pilot chamber 69 for the low speed clutch isincreased more than being compatible with the elastic force of thecompression coil spring 68 for the low speed clutch. Therefore, thespool 67 for the low speed clutch is displaced to the right side of FIG.3 after the hydraulic pressure in the hydraulic chamber 61 for the highspeed clutch is sufficiently increased as shown by a middle portion ofthe bold line c of FIG. 4. Further, the hydraulic pressure in thehydraulic chamber 60 for the low speed clutch starts to be reduced afterthe spool 67 for the low speed clutch is sufficiently displaced to theright side of FIG. 3 as shown by middle portions of the bold line a ofFIG. 4 and the bold line α in FIG. 5B and the low speed clutch 39 b isdisconnected in a state in which the hydraulic pressure in the hydraulicchamber 60 for the low speed clutch is sufficiently reduced.

As is apparent by comparing point A at which the bold line a of FIG. 4and the dashed line β in FIG. 5B representing the oil pressure in thehydraulic chamber 60 for the low speed clutch starts to be reduced andthe low speed clutch 39 b starts to be disconnected and point B at whichthe bold line b of FIG. 4 and the bold line α in FIG. 5B representingthe hydraulic pressure in the hydraulic chamber 61 of the high speedclutch finishes to increase and the high speed clutch 40 b finishes tobe connected, in the case of the embodiment, a moment in which thedriving power is transmitted by the two clutches 39 b, 40 bsimultaneously (a moment of connecting the two clutches 39 b, 40 bsimultaneously) is present although the moment is the short period oftime. Therefore, the torque shift produced at the toroidal-typecontinuously variable transmission 24 in switching the modes can bealleviated.

That is, in the state of simultaneously connecting the two clutches 39b, 40 b, there is constituted a state in which all of the power inputtedto the input shaft 1 is transmitted by the planetary gear typetransmission 25 b and a torque (passing torque) passing thetoroidal-type continuously variable transmission 24 is substantiallynullified. Further, from the state of transmitting the torque from theoutput side disk 5 a to the input side disks 2, 2 in the low speed modeheretofore, the mode is shifted to the high speed mode after temporarilynullifying the passing torque by connecting the two clutches 39 b, 40 b.In the high speed mode, a direction of transmitting the torque isreversed from that in the low speed mode and the torque is transmittedfrom the input side disks 2, 2 to the output side disk 5 a.

In this way, in the case of the embodiment, the apparatus is operatedfor a short period of time by temporarily nullifying the torque passingthe toroidal-type continuously variable transmission 24 when the mode isshifted from the low speed mode to the high speed mode and the directionof the torque passing the toroidal-type continuously variabletransmission 24 is reversed. Further, there is recovered the state inwhich the transmission ratio of the toroidal-type continuously variabletransmission 24 is not influenced by the passing torque (neutral state).The torque shift is produced dividedly in two stages between the lowspeed mode heretofore and the neutral state and between the neutralstate and the new high speed mode. That is, in the respective stages, avariation in the transmission ratio to the toroidal-type continuouslyvariable transmission 24 in accordance with a variation in the passingtorque is produced and the slip rate of the traction portion is changed.The large torque shift is not abruptly produced between the low speedmode and the high-speed mode. As a result, a variation in thetransmission ratio of the total of the continuously variabletransmission apparatus based on the torque shift of the toroidal-typecontinuously variable transmission 24 is made to be gradual and thestrange feeling given to the passenger starting from the driver can bealleviated. Further, durability of a constituent part of the drivingsystem can be promoted by preventing the driving system from beingapplied with the impact. Also in shifting from the high speed mode tothe low speed mode, the torque shift can similarly be alleviated exceptthat the respective portions are reversely operated. Further, in thiscase, the controller stops conducting electricity to the electromagneticswitch valve 78 after making a rotating speed of the ring gear 34 a anda rotating speed of the second carrier 58 substantially coincide witheach other based on controlling the transmission ratio of thetoroidal-type continuously variable transmission 24.

Further, in the case of the embodiment, the following effects of (1)through (3) are also achieved.

(1) A strange feeling can be prevented from being given to a driver byshortening a time period required for switching the mode. That is, inthe case of a structure described in JP-A-9-210191, it is intended tosimultaneously introduce hydraulic pressure into the pressure chambersfor the clutches of the two clutches for high speed and for low speed inswitching the mode to finish to simultaneously connect the two clutches.Further, also in the case of the embodiment, the time period offinishing to simultaneously connect the two clutches in this way canalso be ensured. In such a case, pressures in the pressure chambers forthe clutches of the two clutches are changed as shown by a bold line αand a broken line β of FIG. 5(B) and a time period T required forconnecting and disconnecting the two clutches for switching the mode isprolonged. In contrast thereto, in the case of the embodiment, byadjusting lengths and inner diameters of hydraulic pipes, the pressurereceiving areas of the respective pilot chambers 69, 73 for the lowspeed clutch and for the high speed clutch, elastic constants of therespective compression coil springs 68, 72 for the low speed clutch andfor the high speed clutch and the like, as shown by FIG. 5A, even whenduring a time period of finishing to disconnect connection of the clutch39 b for low speed, the clutch 39 b for low speed and the clutch 40 bfor high speed are not completely connected simultaneously, an instancet′ in which power is transmitted simultaneously by the two clutches 39b, 40 b can be set. When such a setting is carried out, as shown by FIG.5A, a time period T′ required for connecting and disconnecting the twoclutches 39 b, 40 b for switching the mode can be shortened.(2) Further, as described above, it is not necessarily needed tosimultaneously and completely connect the two clutches 39 b, 40 b inswitching the mode and therefore, an increase in the efficiency of thetotal of the continuously variable transmission apparatus can beachieved by restraining an amount of pressurized oil necessary forswitching the mode to be small and restraining an amount of working thepump for supplying the pressurized oil to be small.(3) Further, in the case of the structure of the embodiment, when thecontroller switches only a single piece of the electromagnetic switchvalve 78, thereafter, the time period of simultaneously transmitting thepower by the two clutches can be produced for a short period of timebased on delay time periods in switching the shifting switch valve 74,the switch valve 66 for the low speed clutch and the switch valve 70 forthe high speed clutch all of which are hydraulic type valves. Further,it is not necessary to stop the spool of each valve while it isshifting. Therefore, a structure facilitated to control and difficult tofail can be realized at low cost. Further, a length of the time periodof simultaneously transmitting the power by the low speed clutch 39 band the high speed clutch 40 b based on the delay time periods can becontrolled by the elastic forces of the two compression coil springs 68,72 for the low speed clutch and the high speed clutch included in thetwo switch valves 66, 70 for the low speed clutch and the high speedclutch. Further, the length of the time period can also be controlled byproviding throats at portions between the two switch valves 66, 70 forthe low speed clutch and the high speed clutch and the shifting switchvalve 74 (For example, a, b of FIG. 3) and pertinently restrictingopening degrees of the throats.

Further, it is also possible to ensure a minimum running function whichis needed in bringing the vehicle to a repair shop by running thevehicle by itself by enabling to change the low speed mode and the highspeed mode manually in failing the electromagnetic switch valve 78 byproviding a shifting manual switch valve achieving a function the sameas that of the electromagnetic switch valve manually in parallel withthe electromagnetic switch valve 78 although illustration thereof isomitted. In this case, at a branch portion of a parallel pipelineprovided with the shifting manual switch valve and a main pipelineprovided with the electromagnetic switch valve 78, there is provided aselecting manual switch valve of a three way valve or the like formanually switching the parallel pipeline and the main pipeline.

Further, the hydraulic circuit shown in FIG. 3 is provided with afunction of strictly controlling the torque passing the toroidal-typecontinuously variable transmission 24 and a function of restrainingpower required for driving the respective pressurizing pumps 63, 79 tobe low when the transmission ratio of the continuously variabletransmission apparatus is at a maximum (near to infinity) in the stateof the low speed mode. The reason of providing the function of strictlycontrolling the torque in the functions is as follows. That is, as isapparent from the line segment a of FIG. 2, the continuously variabletransmission apparatus shown in FIG. 1 can produce a state ofso-to-speak infinite transmission ratio for stopping the output shaft 37b in a state of rotating the input shaft 1. In the case of thecontinuously variable transmission apparatus, in the state in which thetransmission ratio is infinite or near thereto, that is, the state inwhich the output shaft 37 b is stopped while rotating the input shaft 1or is rotated at a very low speed, the torque passing the toroidal-typecontinuously variable transmission 24 becomes larger than the torqueapplied from the engine constituting the drive source to the input shaft1. Therefore, in stopping the vehicle or running the vehicle at very lowspeed, the torque inputted from a drive source to the input shaft 1needs to restrict properly such that the torque passing thetoroidal-type continuously variable transmission 24 does not becomeexcessively large (more excessively small).

Further, in running at very low speed, in the state near to the state ofstopping the output shaft 37 b, that is, the state in which thetransmission ratio of the continuously variable transmission apparatusis very large and the rotational speed of the output shaft 37 b is muchslower than the rotational speed of the input shaft 1, the torqueapplied to the output shaft 37 b is considerably varied by a smallvariation in the transmission ratio of the continuously variabletransmission apparatus. Therefore, in order to ensure smooth runningoperation, the torque inputted from the drive source to the input shaft1 still needs to restrain properly.

Therefore, according to the hydraulic circuit shown in FIG. 3, operationas shown by FIG. 6 is carried out in order to properly restrain thetorque inputted from the drive source to the input shaft 1. In theoperation, first, a rotating speed of an engine constituting the drivesource is grossly controlled to restrain to point a within a range w ofFIG. 6. Along therewith, there is set the transmission ratio of thetoroidal-type continuously variable transmission 24, which is needed formaking a rotational speed of the input shaft 1 of the continuouslyvariable transmission apparatus coincide with a controlled rotationalspeed of the engine. The setting operation is carried out based onEquation (1), mentioned above. That is, in the state of the low speedmode, the transmission ratio of the toroidal-type continuously variabletransmission 24 is set by Equation (1), mentioned above, in order toconstitute the rotational speed of the input shaft 1 by a necessaryvalue in correspondence with the rotational speed of the output shaft 37b.

Further, there is measured a pressure difference between the pair ofhydraulic members 10 a, 10 b (refer to FIGS. 3, 18) constituting thehydraulic type actuators 10, 10 for displacing the trunnions 7, 7integrated to the toroidal-type continuously variable transmission 24 inthe axial direction of the pivoting shafts 9, 9 by a hydraulic pressuresensor, not illustrated. The operation of measuring the hydraulicpressure is carried out by grossly controlling the rotational speed ofthe engine (however, in a state of maintaining the rotational speedconstant) and in a state of setting the transmission ratio of thetoroidal-type continuously variable transmission 24 by Equation (1) incorrespondence therewith, as described above. Further, the torqueT_(CVU) passing the toroidal-type continuously variable transmission 24is calculated by the pressure reference calculated based on themeasuring operation. That is, since the pressure difference isproportional to the torque T_(CVU) passing the toroidal-typecontinuously variable transmission 24 so far as the transmission ratioof the toroidal-type continuously variable transmission 24 stays to beconstant, the torque T_(CVU) can be calculated by the pressuredifference.

Meanwhile, the torque T_(CVU) can also be calculated from Equation (3)shown below.T _(CVU) =e _(CVU) ·T _(IN) /{e _(CVU)+(i ₁−1)η_(CVU)}  (3)

In Equation (3), notation e_(CVU) designates the transmission ratio ofthe toroidal-type continuously variable transmission 24, notation T_(IN)designates the torque inputted from the engine to the input shaft 1,notation i₁ designates the ratio of the teeth number m₃₄ of the ringgear 34 a to the teeth number m₅₅ of the first sun gear 55 and notationη_(CVU) designates an efficiency of the toroidal-type continuouslyvariable transmission 24, respectively.

Hence, based on a torque T_(CVU1) actually passing the toroidal-typecontinuously variable transmission 24 and a passing torque T_(CVU2)constituting a target calculated from Equation (3), a deviation ΔT(T_(CVU1)-T_(CVU2)) between the actually passing torque T_(CVU1) and thetarget value T_(CVU2). Further, the transmission ratio of thetoroidal-type continuously variable transmission 24 is controlled in adirection of resolving the deviation ΔT (making ΔT is 0).

For example, consider a case in which as shown by FIG. 6, in a region ofrestraining the torque T_(CVU1) (measured value) actually passing thetoroidal-type continuously variable transmission 24 to the target valueT_(CVU2), the torque T_(IN) of driving the input shaft 1 by the engineis changed in a direction of being reduced rapidly as the rotationalspeed of the input shaft 1 is increased. A characteristic of the engineis easily provided even in the low speed rotating region so far as theengine is an electronically controlled engine. In the case of providingsuch an engine characteristic and when the measured value T_(CVU1) ofthe torque is provided with a deviation in a direction in which therespective input side disks 2, 2 receive the torque from the respectivepower rollers 6, 6 (refer to FIG. 28 through 30) in comparison with thetarget value T_(CVU2), the transmission ratio of the total of thecontinuously variable transmission apparatus is displaced to a speedreducing side in order to increase the rotational speed of the enginefor reducing the torque T_(IN) for driving the input shaft 1. Therefore,the transmission ratio of the toroidal-type continuously variabletransmission 24 is changed to a speed increasing side.

For example, in FIG. 6, when the target value T_(CVU2) is present atpoint a and the measured value T_(CVU1) is present at point b, there isconstituted a state of providing a deviation in the direction in whichthe respective input side disks 2, 2 receive the torque from the powerrollers 6, 6. Hence, the transmission ratio e_(CVT) of the total of thecontinuously variable transmission apparatus is changed to the speedreducing side by changing the transmission ratio e_(CVU) of thetoroidal-type continuously variable transmission 24 to the speedincreasing side. In accordance therewith, the rotational speed of theengine is increased to reduce the torque. On the contrary, when themeasured value T_(CVU1) is present at point c of the drawing, there isconstituted a state of providing a deviation in the direction in whichthe respective input side disks 2, 2 apply torque to the power rollers6, 6. In this case, contrary to the above-described case, thetransmission ratio e_(CVT) of the total of the continuously variabletransmission apparatus is changed to the speed increasing side bychanging the transmission ratio e_(CVU) of the toroidal-typecontinuously variable transmission 24 to the speed reducing side. Inaccordance therewith, the rotational speed of the engine is reduced toincrease the torque.

In the following, the above-described operation is repeatedly carriedout until the torque T_(CVU1) actually passing the toroidal-typecontinuously variable transmission 24 calculated from the pressuredifference coincides with the target value T_(CVU2). That is, theabove-described operation is repeatedly carried out when the torqueT_(CVU1) passing the toroidal-type continuously variable transmission 24cannot be made to coincide with the target value T_(CVU2) only bycontrolling to change the speed of the toroidal-type continuouslyvariable transmission 24 by one time operation. As a result, in thetorque T_(IN) of the engine for driving to rotate the input shaft 1, thetorque T_(CVU1) passing the toroidal-type continuously variabletransmission 24 can be made to be proximate to the target valueT_(CVU2). Further, such operation is carried out automatically and in ashort period of time by instruction from a microcomputer integrated tothe controller of the continuously variable transmission apparatus.

The control for restraining the torque T_(CVU1) actually passing thetoroidal-type continuously variable transmission 24 to point a shown inFIG. 6 constituting the target value T_(CVU2) in this way is divided intwo stages, first, the rotational speed of the engine is controlledgrossly, that is, to the rotational speed which seems to provide thetarget value T_(CVU2) and thereafter, the transmission ratio of thetoroidal-type transmission 24 is controlled in accordance withrotational speed. Therefore, the torque T_(CVU1) actually passing thetoroidal-type continuously variable transmission 24 can be restrained tothe target value T_(CVU2) without bringing about overshooting (andhunting accompanied thereby), or even when the overshooting is assumedlybrought about, by restraining the overshooting to be low to a degreewhich is not problematic practically.

The hydraulic circuit shown in FIG. 3 is provided with the function formaking the torque T_(cvu1) actually passing the toroidal-typecontinuously variable transmission 24 coincide with the target valueT_(CVU2) as described above (torque controlling function) other than thefunction of alleviating the torque shift produced in changing the mode,as described above, as well as a function of restraining power fordriving the respective pressurizing pumps 63, 79 to be low (powerreducing function). For that purpose, according to the hydrauliccircuit, the pressurized oil is made to be able to charge and dischargeto and from the pair of the chambers 80 a, 80 b constituting thehydraulic type actuator 10 for displacing the trunnions 7 in the axialdirections (up and down direction of FIGS. 3, 29) of the pivoting shafts9, 9 (refer to FIG. 29) via the transmission ratio control valve 12 Thesleeve 14 constituting the transmission ratio control valve 12 is madeto be able to drive to displace in the axial direction via a rod 81 anda link arm 82 by the stepping motor 13. Further, the spool 15constituting the transmission ratio control valve 12 is engaged with thetrunnion 7 via the link arm 19, the precess cam 18 and the rod 17 and ismade to be able to drive to displace in the axial direction (left andright direction of FIGS. 3, 29) in accordance with displacement in theaxial direction (up and down direction of FIG. 29) and a pivotingdisplacement of the trunnion 7. The above-described constitution isbasically the same as that of the transmission ratio control mechanismof the toroidal-type continuously variable transmission unit which hasbeen known in the prior art.

Particularly, in the case of the embodiment, in order to provide thetorque controlling function, the sleeve 14 is driven by the steppingmotor 13 and driven also by a hydraulic type pressure differencecylinder 83. That is, a front end portion of the rod 81 a base endportion of which is coupled to the sleeve 14 is axially supported by amiddle portion of the link arm 82 and pins pushed and pulled by thestepping motor 13 or the pressure difference cylinder 83 are engagedwith long holes (that are longitudinal in a upward and downwarddirection of FIG. 3) formed at both end portions of the link arm 82.When one of the pins is pushed or pulled, other of the pins is operatedas a fulcrum. By such a constitution, the sleeve 12 is displaced in theaxial direction by the stepping motor 13 and also by the pressuredifference cylinder 83. In the case of the embodiment, by displacing thesleeve 12 by the pressure difference cylinder 83, in accordance with thetorque T_(CVU) passing the toroidal-type continuously variabletransmission 24, the transmission ratio e_(CVU) of the toroidal-typecontinuously variable transmission 24 is finely controlled.

For that purpose, in the case of the embodiment, the pressurized oil ischarged and discharged to and from a pair of hydraulic chambers 84 a, 84b provided at the pressure difference cylinder 83 by a first and asecond pressure difference control valve 86, 87 controlled by a loadelectromagnetic valve 85 via a forward and rearward switch valve 88. Theload electromagnetic valve 85 is an electromagnetic proportional valveof a normally open type and is provided with a function of introducingthe hydraulic pressure substantially proportional to an applied voltageto the first and the second pressure difference control valves 86, 87present on the downstream side. Further, a valve opening pressure of apressurizing pressure control valve 90 is made to be able to controlbased on opening and closing an electromagnetic valve 89 of a normallyclosed type. Further, states of communicating respective portions aremade to be able to switch by the manual switching valve 64 operated by ashift lever provided at a driver seat.

Further, a difference of the hydraulic pressures of the pair ofhydraulic chambers 80 a, 80 b provided at the actuator 10 for displacingthe trunnion 7 (refer to FIGS. 28, 29) is outputted by a pressuredifference output valve 91 to introduce into the pressurizing pressurecontrol valve 90. A spool 92 constituting the pressure difference outputvalve 91 is displaced in an axial direction in accordance with pressuresin the pair of hydraulic chambers 80 a, 80 b provided by interposing thepiston 16 of the actuator 10 introduced into a pair of hydraulicchambers 93 a, and 93 b. Further, the hydraulic pressure is introducedto a pressure introducing paths 94 a (94 b) respective end portions ofwhich are connected to the pressure difference output valve 91 andreaction chambers 95 a (95 b) provided at the portions opposed to bothend faces of the spool 92 by whether the hydraulic pressure introducedinto one of the pilot portions 93 a (93 b) is higher than the hydraulicpressure introduced into other of the pilot portions 93 b (93 a).

For example, consider a state in which the hydraulic pressure in thehydraulic chamber 80 a for the actuator 10 on one side is higher thanthat of the hydraulic chamber 80 b on other side. Under the state, thehydraulic pressure introduced into the pilot chamber 93 a becomes higherthan the hydraulic pressure introduced into the other pilot portion 93b, the spool 92 is moved to the right side of FIG. 3, and the pressuredifference output valve 91 is switched. As a result, the pressurized oildelivered from the pressurizing pump 63 is introduced to the first pilotportion of the pressurizing pressure control valve 90 via the pressureintroducing path 94 a on one side (right side of FIG. 3). Further, alongtherewith, the pressurized oil is introduced into the first and thesecond pressure difference control valves 86, 87, the pressuredifference cylinder 83 is displaced via the forward and rearward switchvalve 88 and the sleeve 14 of the transmission ratio control valve 12 isfinely displaced.

In contrast thereto, when the hydraulic pressure in the other hydraulicchamber 80 b of the actuator 10 becomes higher than that of the onehydraulic chamber 80 a, the hydraulic pressure introduced into the otherpilot portion 93 b becomes higher than the hydraulic pressure introducedinto the one pilot portion 93 a, the spool 92 is moved to the left sideof FIG. 3 and the pressure difference output valve 91 is switchedreversely to the above-described state. As a result, the pressurized oildelivered from the pressurizing pump 63 is introduced to the secondpilot portion of the pressurizing pressure control valve 90 via thepressure introducing path 94 b on the other side (left side of FIG. 3).Further, along therewith, the pressurized oil is introduced into thefirst and the second pressure difference control valves 86, 87 todisplace the pressure difference cylinder 83 via the forward andrearward switch valve 88.

In either of the cases, the pressurized oil introduced into the pressureintroducing paths 94 a, 94 b is introduced also to the reaction chambers95 a, 95 b of the pressure difference output valve 91 to pressurize theend face in the axial direction of the spool 92. Therefore, a force forcommunicating the pipeline communicated to the pressurizing pump 63 andthe pressure introducing path 94 a (94 b) by displacing the spool 92 inthe axial direction is proportional to a difference |ΔP| of thehydraulic pressures introduced into the pair of pilot portions providedat the pressure difference output valve 91. As a result, the hydraulicpressure introduced into the first and the second pilot portions of thepressurizing pressure control valve 90 is proportional to the difference|ΔP| of the hydraulic pressures in the hydraulic chambers 80 a, 80 b inthe actuator 10, that is, power passing the toroidal-type continuouslyvariable transmission 24 (refer to FIG. 1).

Further, the higher the oil pressure introduced into the first and thesecond pilot portions, the higher the valve opening pressure of thepressurizing pressure control valve 90 provided for providing the powerreducing function. Further, the higher the valve opening pressure of thepressurizing pressure control valve 90, the higher the hydraulicpressure introduced into the hydraulic type pressing apparatus 23 aprovided in place of the mechanical type pressing apparatus 23 (refer toFIGS. 27, 28). Therefore, the larger the power passing the toroidal-typecontinuously variable transmission 24, the larger the hydraulic pressureintroduced into the pressing apparatus 23 a and therefore, the pressingforce produced by the pressing apparatus 23 a. Further, along therewith,an amount of a lubricant delivered from the pressurizing pressurecontrol valve 90 is increased and an amount of the lubricant transmittedto the respective portions of the toroidal-type continuously variabletransmission 24 is increased. Therefore, the efficiency of the total ofthe continuously variable transmission apparatus can be promoted bypreventing power for driving the pressurizing pumps 63, 79 fordelivering the lubricant from being consumed wastefully.

Further, in the above-described hydraulic pressure control circuit, anamount of displacing the spool 15 constituting the transmission ratiocontrol valve 12 by the pressure difference cylinder 83 and therefore,the transmission ratio of the above-described toroidal-type continuouslyvariable transmission 24 is finely controlled by controlling a state ofconducting electricity to the load electromagnetic valve 85 of thenormally open type. Specifically, a controlling computer sets a targetvalue of the torque transmitted to the output shaft 37 b in accordancewith various vehicle states of an accelerator opening degree, a positionof a select lever (position of switching the manual switch valve 64), abraking state and the like. Further, the lower the target value, thehigher the voltage applied to the load electromagnetic valve 15, thesmaller the opening degree of the load electromagnetic valve 85 (smallerthe moment of opening the valve) to thereby reduce the hydraulicpressure introduced into the first and the second pressure differencecontrol valves 86, 87. As a result, the hydraulic pressure introducedinto the pressure difference cylinder 83 via the first and the secondpressure difference control valves 86, 87 is reduced and an amount ofcorrecting the transmission ratio of the toroidal-type continuouslyvariable transmission 24 by the pressure difference cylinder 83 isreduced. Under the state, so far as the spool 15 of the transmissionratio control valve 12 is not displaced by the stepping motor 13, thetorque transmitted to the output shaft 37 b is reduced (to a degreewhich is not sufficient for running the automobile).

Conversely, the higher the target value, the lower the voltage appliedto the load electromagnetic valve 85, the larger the opening degree ofthe load electromagnetic valve 85 (the larger the moment of opening thevalve) to thereby increase the hydraulic pressure introduced into thefirst and the second pressure difference control valves 86, 87 (forexample, 0.45 MPa which is a line pressure). As a result, the hydraulicpressure introduced into the pressure difference cylinder 83 via thefirst and the second pressure difference control valves 86, 87 isincreased and the amount of correcting the transmission ratio of thetoroidal-type continuously variable transmission 24 by the pressuredifference cylinder 83 is increased. Under the state, even when thespool 15 of the transmission ratio control valve 12 is not displaced bythe stepping motor 13, the torque transmitted to the output shaft 37 bis increased to a degree sufficient for running the automobile at lowspeed so far as a brake pedal is not depressed, or a parking brake isnot operated.

In the case of the embodiment, since the load electromagnetic valve 85of the normally open type is used, when electricity conduction to theload electromagnetic valve 85 is cut (applied voltage becomes null) by afailure in an electric control circuit, the hydraulic pressureintroduced into the pressure difference cylinder 83 becomes a maximumvalue and the amount of correcting the transmission ratio of thetoroidal-type continuously variable transmission 24 by the pressuredifference cylinder 83 becomes a maximum value. As a result, in thefailure of the electric control circuit, the torque transmitted to theoutput shaft 37 b can be increased to a degree of capable of running theautomobile at low speed. Further, the automobile failed on the road canbe moved to a safe location of a road shoulder or the like. In otherwords, in the failure of the electric control circuit, when the manualswitch valve 64 is switched to a running state (L, D, R position), thetorque to the degree of capable of running the automobile at low speedcan be applied to the output shaft 37 b. Further, in such a case, it ispreferable to inform the driver of occurrence of the failure by an alarmlight, an alarm buzzer or the like provided on a dashboard in front ofthe driver seat to issue an alarm for preventing the driver from drivingthe vehicle more than necessary for escaping.

Further, FIG. 7 shows a relationship among a ratio of the torque T_(CVU)passing the toroidal-type continuously variable transmission 24 to thetorque T_(IN) of the engine for driving to rotate the input shaft 1(left side ordinate) and the transmission ratio and e_(CVT) of the totalof the continuously variable transmission apparatus (abscissa) and thetransmission ratio e_(CVU) of the toroidal-type continuously variabletransmission 24 (right side ordinate) provided in the low speed mode ofthe continuously variable transmission apparatus constituted andoperated as described above. A bold line a indicates a relationshipbetween the ratio of the passing torque T_(CVU) to the drive torque(engine torque) TIN and the transmission ratio e_(CVT) of the total ofthe continuously variable transmission apparatus and a broken line bindicates a relationship between the two transmission ratios e_(CVT) ande_(CVU), respectively. In the case of the embodiment, the transmissionratio e_(CVU) of the toroidal-type continuously variable transmission 24is restrained in order to restrain the torque T_(CVU1) actually passingthe toroidal-type continuously variable transmission 24 to a targetvalue (T_(CVU2)) represented by a point on the bold line a in a state ofrestraining the transmission ratio of the total of the continuouslyvariable transmission apparatus in a predetermined range.

Embodiment 2

FIG. 8 shows Embodiment 2 of the invention. Also in the case of theembodiment, the transmission ratio of the toroidal type continuouslyvariable transmission 24 (refer to FIG. 1) is adjusted prior to startingto connect one clutch of the clutch 39 b for low speed and the clutch 40b for high speed which has not been connected by a controller 112 inswitching the low speed mode and high speed mode. Successively, the oneclutch is started to connect after making rotational speeds of a pair ofmembers connected via the one clutch substantially coincide with eachother. Further, when power transmission of the one clutch is started,operation of disconnecting connection of other clutch which has beenconnected is started. Further, by providing such a function, there isset an instance of transmitting power simultaneously by the two clutches39 b and 40 b during a time period until connection of the other clutchis disconnected after the one clutch has started to transmit power.

Particularly, in the case of the embodiment, starting of powertransmission by the one clutch is detected by hydraulic pressure atinside of the hydraulic chamber for the clutch for introducing hydraulicpressure in connecting the clutch. For that purpose, in the case of theembodiment, hydraulic pressure at inside of the hydraulic chamber 60 forthe low speed clutch belonging to the clutch 39 b for low speed is madeto be electrically detectable by a pressure meter 113 a constituting apressure sensor and hydraulic pressure at inside of the hydraulicchamber 61 for the high speed clutch belonging to the clutch 40 b forhigh speed is made to be electrically detectable by a pressure meter 113b constituting a pressure sensor. As is apparent from the bold line b ofFIG. 4 and the bold lines α of FIGS. 5A and 5B explained in Embodiment1, mentioned above, starting of power transmission of the one clutchwhich has not been connected can be grasped by observing hydraulicpressure at inside of the hydraulic chamber for the clutch belonging tothe clutch. Hence, when it is determined that power transmission of theone clutch which has not been connected is started based on a signalfrom either of the pressure meter 113 a (or 113 b), the controller 112disconnects connection of the other clutch which has been connected.

As a result, also in the case of the embodiment, similar to the case ofEmbodiment 1, mentioned above, as shown by FIG. 5A, the instance ofsimultaneously transmitting power by the two clutches is firmly producedand the torque shift brought about in the toroidal type continuouslyvariable transmission in switching the mode can be alleviated.

Further, although illustration is omitted, in order to detect that powertransmission of the one clutch which has not been connected is started,the detection can also be carried out by detecting a stroke(displacement) of a piston which is a driving member for connecting theclutch by a displacement meter of a potentiometer or the like installedat the piston or a portion displaced along with a piston.

Further, whereas in the case of the embodiment, starting of powertransmission by the respective clutch 39 b, 40 b for low speed and forhigh speed is electrically detected by the pressure meters 113 a, 113 bconstituting the pressure sensors as described above, in the case of thestructure of Embodiment 1 shown in FIGS. 1 through 7, mentioned above,starting of power transmission by the respective clutches 39 b, 40 b forlow speed and for high speed is mechanically detected by the respectiveswitching valves 66, 70 for the low speed clutch and for high speedclutch switched in accordance with introduction of hydraulic pressureinto the respective hydraulic chambers 60, 61 for the low speed clutchand for the high speed clutch of the respective clutches 39 b, 40 b.Further specifically, in the case of the structure of Embodiment 1,mentioned above, by setting elastic forces of the respective compressioncoil springs 68, 72 for the low speed clutch and for the high speedclutch constituting the respective switching valves 66, 70 for the lowspeed clutch and for the high speed clutch such that after startingpower transmission by one clutch (for example, the clutch 40 b for highspeed) of the clutch 39 b for low speed and the clutch 40 b for highspeed which has not been connected, connection of other clutch (forexample, the clutch 39 b for low speed) which has been connected isdisconnected, the above-described respective switching valves 66, 70 areprovided with a function equivalent to that of detecting starting ofpower transmission by the one clutch 40 b (39 b). That is, hydraulicpressures necessary for connecting the respective clutch 39 b, 40 b forlow speed and for high speed are determined by magnitudes of elasticforces of the springs (return springs) 121 a, 121 b (refer to FIG. 3)for the clutches for bringing the respective clutches 39 b, 40 b into anunconnected state. In other words, at the time point at which productsof hydraulic pressures in the hydraulic chambers 60, 61 of the clutchesof the respective clutches 39 b, 40 b by the pressure receiving areas ofthe pistons constituting the respective clutches 39 b, 40 b becomelarger than the elastic forces of the springs 121 a, 121 b of theclutches of the respective clutches 39 b, 40 b, operation of connectingthe respective clutches 39 b, 40 b is started to start transmittingpower. Therefore, when the elastic forces of the respective compressioncoil springs 68, 72 for the low speed clutch and for the high speedclutch are set such that connection of the other clutch 39 b (40 b) isdisconnected by hydraulic pressure equal to or larger than hydraulicpressure necessary for displacing the piston of the one clutch 40 b (39b) to a position of starting to transmit power, starting of powertransmission by the one clutch 40 b (39 b) is mechanically detected bythe switching valve 70 (66) (without using the pressure sensors) andconnection of the other clutch 39 b (40 b) can be disconnected by theswitching valve 70 (66).

Further, in the case of a structure of pressing the respective spools67, 71 in an opening direction by hydraulic pressures introduced intorespective reaction force chambers 114, 115 for the low speed clutch andfor the high speed clutch as in Embodiments 5 through 7 shown in FIGS.15 through 19, mentioned later, by setting the ratios of the pressurereceiving areas of the respective reaction force chambers 114, 115 andthe respective pilot chambers 69, 73 for the low speed clutch and forthe high speed clutch, connection of the other clutch 39 b (40 b) isdisconnected by hydraulic pressure equal to or larger than hydraulicpressure necessary for displacing the piston of the one clutch 40 b (39b) to the position of starting to transmit power. When constituted inthis way, even in the structure in which the respective switching valves66, 70 for the low speed clutch and for the high speed clutch areprovided with the reaction force chambers 114, 115, by the respectiveswitching valves 66, 70 starting of power transmission by the one clutch40 b (39 b) is mechanically detected (without using the pressuresensors) and connection of the other clutch 39 b (40 b) can bedisconnected by the respective switching valves 66, 70.

Embodiment 3

FIG. 9 shows Embodiment 3 of the invention. In the case of theembodiment, by providing a first throat 97 constituting first resistingmeans and a second throat 98 constituting second resisting means, thereis firmly provided a time period from when one clutch of the two lowspeed and high speed clutches 39 b, 40 b, which has been disconnected towhen other clutch thereof which has been connected is disconnected.

For that purpose, the first throat 97 is provided at a middle of a firstpressure introducing path 99 for introducing the hydraulic pressureintroduced into the hydraulic chamber 61 for the high speed clutch intothe pilot chamber 69 for the low speed clutch belonging to the switchvalve 66 for the low speed clutch via the shift switch valve 74. Thefirst throat 97 having any structure can be utilized so far as the firstthroat 97 is a member constituting a resistance against flow of thepressurized oil of an orifice, a capillary tube or the like. The firstthroat 97 constitutes a resistance against introduction of the hydraulicpressure introduced into the hydraulic chamber 61 for the high speedclutch belonging to the high speed clutch 40 b into the pilot chamber 69for the low speed clutch and an increase in the pressure in the pilotchamber 69 for the low speed clutch is retarded in comparison with anincrease in the pressure in the hydraulic chamber 61 for the high speedclutch.

Therefore, when the hydraulic pressure is introduced into the hydraulicchamber 61 for the high speed clutch in accordance with switching fromthe low speed mode to the high speed mode, the hydraulic pressure in thehydraulic chamber 61 for the high speed clutch swiftly rises and thehigh speed clutch 40 b is immediately connected. In contrast thereto,rise of the hydraulic pressure in the pilot chamber 69 for the low speedclutch is retarded based on presence of the first throat 97 andswitching of the switch valve 66 for the low speed clutch is retarded.As a result, a reduction in the hydraulic pressure in the hydraulicchamber 60 for the low speed clutch for the low speed clutch 39 b isretarded and during the time period, both of the low speed clutch 39 band the high speed clutch 40 b stay to be connected.

Further, the second throat 98 is provided at a middle of a secondpressure introducing path 100 for introducing the hydraulic pressureintroduced into the hydraulic chamber 60 for the low speed clutch intothe pilot chamber 73 for the high speed clutch belonging to the switchvalve 70 for the high speed clutch via the shifting switch valve 74. Thesecond throat 98 is constituted by a structure similar to that of thefirst throat 97 and constitutes a resistance against introduction of thehydraulic pressure introduced into the hydraulic chamber 60 for the lowspeed clutch belonging to the low speed clutch 39 b into the pilotchamber 73 for the high speed clutch to thereby retard an increase inthe pressure in the pilot chamber 73 for the high speed clutch incomparison with an increase in the pressure in the hydraulic chamber 60for the low speed clutch.

Therefore, when the hydraulic pressure is introduced into the hydraulicchamber 60 for the low speed clutch in accordance with switching fromthe high speed mode to the low speed mode, the hydraulic pressure in thehydraulic chamber 60 for the low speed clutch rapidly rises, whereby thelow speed clutch 39 b is immediately connected. In contrast thereto,rise of the hydraulic pressure in the pilot chamber 73 for the highspeed clutch is retarded based on presence of the second throat 98 andswitching of the switch valve 70 for the high speed clutch is retarded.As a result, a reduction in the hydraulic pressure in the hydraulicchamber 61 for the high speed clutch of the high speed clutch 40 b isretarded and during the time period, both of the high speed clutch 40 band the low speed clutch 39 b stay to be connected.

As described above, in the case of the embodiment, there is firmlyprovided a time period from when one clutch of the two low speed andhigh speed clutches 39 b, 40 b which has been disconnected to when otherclutch thereof which has been connected is disconnected. That is, thetime period of simultaneously transmitting the power by the low speedand high speed clutches 39 b, 40 b, (between A and B in theabove-mentioned FIGS. 4 and 5) can firmly be produced by ensuring thedelay time period of switching the hydraulic type valve.

Constitution and operation thereof other than providing the first throat97 and the second throat 98 are similar to those of Embodiment 1,mentioned above, and therefore, duplicated illustration and explanationwill be omitted. Further, the first and the second throats 97, 98 may beprovided between the shifting switch valve 74 and the respective pilotchambers 69, 73 for the low speed clutch and for the high speed clutchin the first and the second pressure introducing paths 99, 100. However,in this case, it is preferable to provide check valves which are openedwhen the hydraulic pressure in the respective pilot chambers 69, 73 aredischarged in parallel with the first and the second throats 97, 98. Thereason is that time periods required for connecting the respective lowspeed and high speed clutches 39 b, 40 b are shortened by swiftlyreducing the hydraulic pressures in the respective pilot chambers 69, 73by switching the modes. In contrast thereto, when the first and thesecond throats 97, 98 are provided between the shifting switch valve 74and the respective hydraulic chambers 60, 61 for the low speed clutchand for the high speed clutch in the first and the second pressureintroducing paths 99, 100 as shown by FIG. 9, the check valves are notneeded, which is advantageous in view of a reduction in cost andensuring an installing space.

Embodiment 4

FIGS. 10 through 14 show Embodiment 4 of the invention. In the case ofthe embodiment, the elastic force of the compression coil spring 72 forthe high speed clutch constituting the elastic member for the high speedclutch for elastically pressing the spool 71 for the high speed clutchintegrated to a switch valve 70 a for the high speed clutch related tothe high speed clutch 40 b which is the clutch which is not to beconnected in starting the vehicle, is made variable. Specifically, theembodiment is constituted such that in the running state (running mode),that is, in the case in which the manual switch valve 64 switched by theshift lever provided by the driver seat is switched to any of L (lowrange), D (drive range), and R (reverse range), the elastic force of thecompression coil spring 72 for the high speed clutch is made to be largeand in the non-running state, that is (non-running mode), in the case inwhich the manual switch valve 64 is switched to either of N (neutralrange) and P (parking range), the elastic force of the compression coilspring 72 for the high speed clutch is set to be small.

The reason that according to the embodiment, the elastic force of thecompression coil spring 72 for the high speed clutch is made variable asdescribed above is as follows. As described above, in order to preventan abrupt variation in the transmission ratio from being brought aboutin switching the low speed mode and the high-speed mode, it is effectiveto produce the time period of simultaneously connecting the low speedclutch 39 b and the high speed clutch 40 b by a short period of time. Inthe case of the structure of Embodiment 1 shown by FIG. 3 which isconstituted with such a purpose, in order to firmly produce the timeperiod of simultaneously transmitting the power by the two clutches 39b, 40 b, it is preferable to increase the elastic forces of therespective compression coil springs 68, 72 for the low speed clutch andthe high speed clutch integrated to the respective switch valves 66, 70for the low speed clutch and the high speed clutch.

When the elastic forces of the respective compression coil spring 68, 72are small, depending on a structure of a hydraulic pipe, there is apossibility that the respective spools 67, 71 for the low speed clutchand the high speed clutch integrated to the respective switch valves 66,70 are displaced at an early stage, the pressure in the hydraulicchamber of the clutch which has been connected is discharged in a shortperiod of time so that the time period of simultaneously transmittingthe power by the two clutches 39 b, 40 b cannot be provided. FIGS. 13through 14 show a result of an experiment which is carried out withrespect to a state of switching the manual switch valve 64 from thenon-running state to running state in this regard. FIG. 13 of thedrawings show a case in which the compression coil spring 72 for thehigh speed clutch is large and FIG. 14 shows a case in which the elasticforce is small, respectively. Further, in FIGS. 13 through 14, a boldline a shows a hydraulic pressure at a portion of a delivery port of thepressurizing pump 63 (see FIG. 3), a slender line b shows a hydraulicpressure in the hydraulic chamber 60 for the low speed clutch, a brokenline c shows a hydraulic pressure in the hydraulic chamber 6 for thehigh speed clutch, a one-dotted chain lined shows a movement of the lowspeed clutch 39 b (stroke of actuator), and a two-dotted chin line eshows a movement of the high speed clutch 40 b, respectively. As isapparent from FIGS. 13 through 14, when the elastic forces of therespective compression coil springs 68, 72 are excessively small, thetime period of simultaneously connecting the two clutches 39 b, 40 b isnot provided, however, when the elastic forces of the respectivecompression coil springs 68, 72 are increased, the time period ofsimultaneously connecting the two clutches 39 b, 40 b is provided.

However, when the elastic forces of the respective compression coilsprings 68, 72 are simply increased, there poses a new problem thatimpact is applied in starting the vehicle. That is, in the case in whichthe manual switch valve 64 is switched from N or P position to any of L,D, R positions in order to start a vehicle which has been in astationary state, when the elastic forces of the respective coil springs68, 72 are large as shown by FIG. 11, there is produced the time periodof simultaneously connecting the two clutches 39 b, 40 b although thetime period is short. Meanwhile, at a moment of switching the manualswitch valve 64 from N or P position to any of N, D, R in order to startthe vehicle, the transmission ratio of the toroidal-type continuouslyvariable transmission 24, 24 a (FIGS. 1, 30, 31) becomes a transmissionratio pertinent for starting.

For example, in the case of the continuously variable transmissionapparatus of the geared neutral type shown in FIG. 1, 30, thetransmission ratio of the toroidal-type continuously variabletransmission 24 is present comparatively on the speed increasing sideand in the case of the continuously variable transmission apparatus ofthe power split type shown in FIG. 31, the transmission ratio of thetoroidal-type continuously variable transmission 24 a is present on themostly speed reducing side. Also in the case of either of thecontinuously variable transmissions, the transmission ratio of thetoroidal-type continuously variable transmission 24, 24 a in startingsignificantly differs from that of the state of changing the modes forconnecting or disconnecting the two clutches 39 b, 40 b. When the twoclutches 39 b, 40 b are simultaneously connected under the state even ina short period of time, an excessive force is exerted to each portion ofthe constitution of the continuously variable transmission apparatus, animpact giving unpleasant feeling to the passenger starting from thedriver is brought about and durability of each member of theconstitution is reduced.

In contrast thereto, in the case of the embodiment, the elastic force ofthe compression coil spring 72 for the high speed clutch integrated tothe switch valve 70 a for the high speed clutch for controlling tointroduce the pressurized oil into the hydraulic chamber 61 for thehigh-speed clutch belonging to the high speed clutch 40 b, is increasedonly in a running state of changing the modes. Conversely, the elasticforce of the compression coil spring 72 for the high speed clutchrelated to the high speed clutch 40 b which is not to be connected instarting is made to be small in the non-running state and in switchingfrom the non-running state to starting, the high speed clutch 40 b isprevented from being connected. The elastic force of the compressioncoil spring 68 for the low speed clutch integrated to the switch valve66 for the low speed clutch for controlling to introduce the pressurizedoil into the hydraulic chamber 60 for the low speed clutch belonging tothe low speed clutch 39 b may stay to be large and therefore, a controlmechanism is not particularly provided.

In order to control the elastic force of the compression coil spring 72for the high speed clutch, in the case of the embodiment, a cylinderportion 101 is provided at an end portion of the switch valve 70 a forthe high speed clutch at a position in the axial direction opposed tothe pilot chamber 73 for the high speed clutch by interposing the spool71 for the high speed clutch and a pressing piston 102 is provided inthe cylinder portion 101 displaceably in an axial direction (left andright direction of FIGS. 10 through 12). The length in the axialdirection of the cylinder portion 101 is made to be slightly longer thanthat of the pressing piston 102 and the pressing piston 102 isdisplaceable in the axial direction by an amount of a difference betweenthe lengths. Further, the compression coil spring 72 for the high speedclutch is arranged between the pressing piston 102 and the spool 71 forthe high speed clutch. Further, a portion in the cylinder portion 101 ona side opposed to the spool 71 for the high speed clutch is made to beable to introduce the pressurized oil from the manual switch valve 64via a throat 103.

That is, the pressurized oil is introduced to the portion in thecylinder portion 101 on the side opposed to the spool 71 for the highspeed clutch in the state in which the manual switch valve 64 isswitched to the running state (L, D, R position) In contrast thereto, ina state in which the manual switch valve 64 is switched to thenon-running state (N, P position), the portion in the cylinder portion101 on the side opposed to the spool 71 for the high speed clutch isreleased to the oil storage 62. Further, the throat 103 is provided fordelaying a displacement of the pressing piston 102 to for firmly preventthe high speed clutch 40 b from being connected in switching the manualswitch valve 64 from the non-running state to the running state forstarting.

In the case of the embodiment, in order to constitute the switch valve70 a of the high speed clutch as described above, in the non-runningstate, as shown by FIG. 11, the pressing piston 102 is pressed by thecompression coil spring for the high speed clutch to move to an endportion of the cylinder portion 101 on a side remote from the spool 71for the high speed clutch (left side of FIG. 11). Under the state, theelastic force of the compression coil spring 72 for the high speedclutch is reduced, and even at the moment of switching the manualswitching valve 64 from the non-running state (N, P position) to therunning state (L, D, R position), as shown by FIG. 14, the high speedclutch 40 b is not connected even for a short period of time.

In contrast thereto, in the running state, the pressing piston 102 ismoved to an end portion of the cylinder portion 101 on a side of thespool 71 for the high speed clutch (right side of FIG. 12) due to ahydraulic pressure introduced in the cylinder portion 101, as shown inFIG. 12. Under the state, the elastic force of the compression coilspring 72 for the high speed clutch is increased. As a result, inswitching, for example, from the high speed made to the low speed mode,the time period of simultaneously connecting the two clutches 39 b, 40 bis firmly provided. As described above, the elastic force of thecompression coil spring 68 for the low speed clutch integrated to theswitch valve 66 for the low speed clutch is large and therefore, even inswitching from the low speed mode to the high speed mode, the timeperiod of simultaneously connecting the two clutches 39 b, 40 b canfirmly be provided.

Embodiment 5

FIG. 15 shows Embodiment 5 of the invention. In the case of theembodiment, the two spools 67, 71 for the low speed clutch and for thehigh speed clutch constituting the two switching valves 66, 70 for thelow speed clutch and for the high speed clutch are pressed in a closingdirection also by hydraulic pressure introduced into the two reactionforce chambers 114, 115 for the low speed clutch and for the high speedclutch in addition to the elastic forces of the compression coil springs68, 72 respectively for the low speed clutch and for the high speedclutch. Therefore, value opening pressures of the switching valves 66,70 for the low speed clutch and the high speed clutch, that is,hydraulic pressures necessary for being introduced into the two pilotchambers 69, 73 respectively for the low speed clutch and for the highspeed clutch for communicating the hydraulic chamber 60 for the lowpressure clutch or the hydraulic chamber 61 for the high pressure clutchto the oil storage 62 are adjustable based on the hydraulic pressuresintroduced into the two reaction force chambers 114, 115 for the lowspeed clutch and for the high speed clutch.

In the case of the embodiment, hydraulic pressures constituted bycontrolling hydraulic pressure at a portion of a delivery port of thepressurizing pump 63 on the high pressure side to predeterminedpressures by pressure control valves 116 a, 116 b of an electric typehaving a pressure controlling function of an electromagneticproportional valve or the like are introduced into the two reactionchambers 114, 115 for the low speed clutch and for the high speedclutch. Further, hydraulic pressures controlled by a single pressurecontrol valve may be introduced into the two reaction force chambers114, 115. The two reaction force chambers 114, 115 are present on sidesopposed to the pilot chambers 69, 73 for the low speed clutch and forthe high speed clutch in axial directions by interposing the two spools67, 71 for the low speed clutch and for the high speed clutch andtherefore, the higher the hydraulic pressures introduced into the tworeaction force chambers 114, 115, the higher the valve opening pressuresof the two switching valves 66, 70 for the low speed clutch and for thehigh speed clutch. The valve opening pressures of the two switchingvalves 66, 70 are adjusted in view of design by hydraulic pressuresintroduced into the two reaction force chambers 114, 115 and pressurereceiving areas of two end portions of the two spools 67, 71 in axialdirections.

Also in the case of the embodiment, there is provided the manualswitching valve 64 (refer to FIG. 3) switched to the running mode(running state) and the nonrunning mode (nonrunning state) by the shiftlever installed at the driver's seat. Further, when the manual switchingvalve 64 is switched to the nonrunning mode (nonruning state=P range orN range), pressurized oil is stopped to be introduced into the tworeaction force chambers 114, 115. Under the state, the valve openingpressures of the two switching valves 66, 70 for the low speed clutchand for the high speed clutch are lowered. Further, even when the manualswitching valve 64 is switched to the running mode (running state=Drange or R range) from the state, as is apparent from FIG. 14, mentionedabove, only the clutch necessary in the running state at the time pointis connected. In other words, also the clutch which is not to beconnected in the running state at the time point is not connected.Therefore, by preventing the two clutches 39, 40 for low speed and forhigh speed from being connected simultaneously at the instance ofswitching from the nonrunning state to the running state withoutswitching the low speed mode and the high speed mode, an unpleasantfeeling can be prevented from being given to a passenger or durabilitiesof respective constituent portions can be prevented from beingdeteriorated by bringing about impact.

Further, in the case of the embodiment, reason of not only lowering thevalve opening pressure of the switching valve for the high speed clutchbut also lowering the valve opening pressure of the switching valve 66for the low speed clutch when the manual switching valve 64 is broughtinto the nonrunning state is for considering a case in which the driverselects the nonrunning mode {neutral (N) range} for operational failureor running inertia in running at high speed (although not preferable).In such a case, after selecting the nonrunning mode, when the nonrunningmode is returned to the running mode {drive (D) range} while staying inthe running state at high speed, in the case in which the clutch (theclutch 39 b for low speed) which is not be connected under the state isconnected although the time period is short, the above-described impactis brought about. In contrast thereto, in the case of the embodiment,when the manual switching valve 64 is brought into the nonrunning state,not only the valve opening pressure of the switching valve 70 for thehigh speed clutch is lowered but also the valve opening pressure of theswitching valve 66 for the low speed clutch is lowered and therefore,the above-described impact can be prevented from being applied bypreventing the clutch 39 b for low speed from being connected when themanual switching valve 64 is returned to the running mode.

Further, there is also conceivable a case in which the manual switchingvalve 64 is brought into the nonrunning state in running not only inrunning at high speed but also in running at low speed. Therefore, whenthe manual switching valve 64 is returned to the running state inrunning, one clutch of the clutch 39 b for low speed and the clutch 40 bfor high speed is connected in accordance with a vehicle speed (orrotational speed of an engine) at a time point of switching from thenonrunning mode to the running mode. For that purpose, the controllerfor controlling to connect and disconnect the two clutches 39 b, 40 b isinputted with a signal indicating the vehicle speed (or the rotationalspeed of the engine). Further, the controller switches the shiftingswitch valve 74 by the electromagnetic switching valve 78 (refer to FIG.3) in accordance with switching from the nonrunning mode to the runningmode and connects the clutch 40 b for high speed in running at speed(for example, in a case of being equal or faster than 30 km/h) andconnects the clutch 39 b for low speed in running at low speed (forexample, in a case of being less than 30 km/h). The other clutch is madeto stay to be in the unconnected state. Even when either of the clutchesis connected, in the case of switching to the nonrunning mode asdescribed above, the valve opening pressures of the two switching valves66, 70 for the low speed clutch and for the high speed clutch are lowand therefore, only the necessary clutch is connected and the clutchwhich is not to be connected is not connected (there is not an instanceof simultaneously connecting the two clutches 39 b, 40 b).

Embodiment 6

FIG. 16 shows Embodiment 6 of the invention. In the case of theembodiment, hydraulic pressure delivered from the pressurizing pump 63on the high pressure side and lowered by passing the pressure reducingvalve 65 is introduced into the two reaction force chambers 114, 115 forthe low speed clutch and for the high speed clutch in accordance withreleasing electromagnetic valves 117 a, 117 b. The hydraulic pressureintroduced into the two reaction force chambers 114, 115 may beconstituted by passing a single electromagnetic valve. Further, althoughthe electromagnetic valve may be a pressure control valve, theelectromagnetic valve may be an opening/closing valve for switching onlyto ON-OFF. The other constitution and operation are similar to those ofEmbodiment 6, mentioned above.

Embodiment 7

FIGS. 17 through 19 show Embodiment 7 of the invention. Also in the caseof the embodiment, similar to Embodiment 6, mentioned above, thehydraulic pressure delivered from the pressurizing pump 63 on the highpressure side and lowered by passing the pressure reducing valve 65 isintroduced into the two reaction force chambers 114, 115 for the lowspeed clutch and for the high speed clutch provided at the two switchingvalves 66, 70 for the low speed clutch and for the high speed clutch.However, in the case of the embodiment, the introduction is constitutedto carry out purely hydraulically. That is, in the case of theembodiment, when the manual switching valve 64 (refer to FIG. 3) selectsthe running state (running mode) by the shift lever installed at thedriver's seat, so far as there are present hydraulic pressures in thehydraulic chambers 60, 61 for the clutches belonging to the connectedclutches of the clutch 39 b for low speed and the clutch 40 b for highspeed, hydraulic pressure adjusted to a predetermined pressure by thepressure reducing valve 65 is constituted to introduce into the tworeaction chambers 114, 115 for the low speed clutch and for the highspeed clutch via a hydraulic pressure introducing valve 118 switchedhydraulically.

The above-described hydraulic pressure introducing valve 118 is providedwith a pair of spools 119 a, 119 b which are movable remotely andproximately and a single piece of compression coil spring 120.

In the low speed mode, when hydraulic pressure is present at inside ofthe hydraulic chamber 60 and hydraulic pressure is not present in thehydraulic chamber 61 for the high speed clutch, according to thehydraulic pressure introducing valve 118, as shown by FIG. 17, the twospools 119 a, 119 b are displaced in directions of being remote fromeach other. Under the state, hydraulic pressure controlled to thepredetermined pressure by the pressure reducing valve 65 is introducedinto the two reaction chambers 114, 115 for the low speed clutch and forthe high speed clutch by passing the hydraulic pressure introducingvalve 118. Therefore, the valve opening pressures of the two switchingvalves 66, 70 for the low speed clutch and for the high speed clutch,that is, hydraulic pressures necessary for being introduced to the twopilot chambers 69, 73 respectively for the low speed clutch and for thehigh speed clutch for communicating the hydraulic chamber 60 for the lowspeed clutch or the hydraulic chamber 61 for the high speed clutch tothe oil storage 62 is increased. As a result, in switching from the lowspeed mode to the high speed mode, an instance of simultaneouslytransmitting power by the clutch 39 b for low speed and the clutch 40 bfor high speed can firmly be realized.

Further, in the high speed mode, when hydraulic pressure is present inthe hydraulic chamber 61 for the high speed clutch and hydraulicpressure is not present in the hydraulic chamber 60 for the low speedclutch, according to the hydraulic pressure introducing valve 118, asshown by FIG. 18, the two spools 119 a, 119 b are displaced against thecompression coil spring 120 in a state of butting the two spools 119 a,119 b. Also under the state, hydraulic pressure controlled to thepredetermined pressure by the pressure reducing valve 65 is introducedinto the two reaction force chambers 114, 115 for the low speed clutchand for the high speed clutch by passing the hydraulic pressureintroducing valve 118. Therefore, the valve opening pressures of the twoswitching valves 66, 70 for the low speed clutch and for the high speedclutch, that is, hydraulic pressures necessary for being introduced intothe two pilot chambers 69, 73 respectively for the low speed clutch andfor the high speed clutch for communicating the hydraulic chamber 60 forthe low speed clutch or the hydraulic chamber 61 for the high speedclutch to the oil storage 62 is increased. As a result, in switchingfrom the high speed mode to the low speed mode, an instance ofsimultaneously transmitting power by the clutch 39 b for low speed andthe clutch 40 b for high speed can firmly be realized.

In contrast thereto, when the manual switching valve 64 selects thenonunning state (nonrunning mode) and hydraulic pressure is not presentin either of the two hydraulic chambers 60, 61 for the low speed clutchand for the high speed clutch, according to the hydraulic pressureintroducing valve 118, as shown by FIG. 19, the two spools 119 a, 119 bare displaced (to the right side of FIG. 19) based on the compressioncoil spring 120 in a state of butting the two spools 119 a, 119 b. Underthe state, the two reaction force chambers 114, 115 for the low speedclutch and for the high speed clutch are communicated to the oil storage62 and the valve opening pressures of the two switching valves 66, 70for the low speed clutch and for the high speed clutch are lowered. As aresult, in switching from the nonrunning state to the running state, theclutch which is not to be connected under the state is prevented frombeing connected although time interval is short and the impact can beprevented from being brought about.

Constitutions of operation of the other portions are similar to those ofEmbodiments 5, 6, mentioned above.

Embodiment 8

Next, FIG. 20 shows Embodiment 8 of the invention. In the case of theembodiment, there are provided throats 103 of orifices, throttle valves,capillary tubes or the like respectively between the switch valve 66 forthe low speed clutch and the oil storage 62 and between the switch valve70 for the high speed clutch and the oil storage 62. In the case of theembodiment, by such a constitution, the shifting switch valve 74 isswitched and the clutch which has been disconnected is finished toconnect before disconnecting the clutch which has been connected.

For example, an explanation will be given of a state immediately afterthe shifting switch valve 74 is switched to a state shown in FIG. 20 andthe two switch valves 66, 70 for the low speed clutch and the high speedclutch are switched to a state shown in the drawing in accordancetherewith. Under the state, the pressurized oil passing the pressurereducing valve 65 (refer to FIG. 3) is delivered into the hydraulicchamber 60 for the low speed clutch while passing the switch valve 66for the low speed clutch without particularly undergoing a resistance toconnect the low speed clutch 39 b in an extremely short period of time.Meanwhile, the pressurized oil in the hydraulic chamber 61 for the highspeed clutch passes the switch valve 70 for the high speed clutch andundergoes a resistance by the throat 103 to be gradually discharged tothe oil storage 62.

Therefore, a time period required until disconnecting the high speedclutch 40 b is longer than a time period required until connecting thelow speed clutch 39 b. As a result, the low speed clutch 39 b which hasbeen disconnected is finished to connect before disconnecting the highspeed clutch 40 b which has been connected. When the switching switchvalve 74 is switched reversely to the state shown in FIG. 20, theembodiment is similarly operated other than reversing connection anddisconnection of the two clutches 39 b, 40 b, and the high speed clutch40 b which has been disconnected is finished to connect beforedisconnecting the low speed clutch 39 b which has been connected.Therefore, similar to the above-described cases of Embodiments 1 through7, the torque shift produced in switching the modes can be alleviated.Further, in the case of the embodiment, a structure for simultaneouslyconnecting the two clutches 39 b, 40 b for a short period of time isrealized by simply adding the throat and therefore, a structurefacilitated to control and difficult to fail can be realized at lowcost. Constitution and operation of other portions are similar to thoseof Embodiment 1 shown in FIGS. 1 through 7 and therefore, a duplicatedexplanation will be omitted.

Embodiment 9

FIG. 21 shows Embodiment 9 of the invention. In the case of theembodiment, a single hydraulic pressure discharge path 104 isconstituted by merging a downstream portion of a hydraulic pressuredischarge path on a side of the low speed clutch connecting the switchvalve 66 for the low speed clutch and the oil storage 62 and adownstream portion of a hydraulic pressure discharge path on a side ofthe high speed clutch connecting the switch valve 70 for the high speedclutch and the oil storage 62. Further, a single throat 103 is providedat a portion of the single hydraulic pressure discharge path 104.

In the case of the embodiment having such a constitution, when theswitch valve 66 for the low speed clutch or the switch valve 70 for thehigh speed clutch is switched to a state of communicating the hydraulicchamber 60 for the low speed clutch or the hydraulic chamber 61 for thehigh speed clutch to the oil storage 62 based on switching of theshifting switch valve 74, the pressurized oil in the hydraulic chamberis discharged to the oil storage 62 via the single throat 103.

In the case of the embodiment, the oil pressures in the two hydraulicpressure chambers 60, 61 can gradually be reduced by the single throat103 and small-sized and light-weighed formation can be achieved byreducing cost by reducing a number of parts and a number of integratingsteps and an installation space.

Embodiment 10

FIG. 22 shows Embodiment 10 of the invention. In the case of theembodiment, at a vicinity of the hydraulic chamber 60 for the low speedclutch or the hydraulic chamber 61 for the high speed clutch as in aportion F or a portion G of FIG. 13, a structure of a portion of ahydraulic path for charging and discharging a pressurized oil to andfrom each of the hydraulic chambers 60, 61 is devised. Specifically,instead of smoothly delivering the pressurized oil into the respectivehydraulic chambers 60, 61, the hydraulic pressure is graduallydischarged from the respective hydraulic chamber 60, 61.

For example, at a portion at a vicinity of the hydraulic chamber 60 forthe low speed clutch (F portion of FIG. 20) and constituting a singlelow pressure side hydraulic path 105 by merging a low speed clutch sidepressure introducing path (a second pressure introducing path 100) and alow speed clutch side pressure discharging path, a low speed clutch sidecheck valve 106 which is opened in introducing the hydraulic pressureinto the hydraulic chamber 60 for the low speed clutch and closed indischarging the hydraulic pressure from the hydraulic chamber 60 for thelow speed clutch and a low speed clutch side throat 107 are provided inparallel with each other. Further, also at a portion at a vicinity ofthe hydraulic chamber 60 for the high speed clutch and constituting asingle high pressure side hydraulic pressure path 108 (G portion of FIG.13) by merging a high speed clutch side pressure introducing path (afirst pressure introducing path 99) and a high speed clutch sidepressure discharging path, a high speed clutch side check valve which isopened in introducing the hydraulic pressure into the hydraulic chamber61 for the high speed clutch and closed in discharging the hydraulicpressure from the hydraulic chamber 61 for the high speed clutch and ahigh speed clutch side throat (not illustrated) are provided in parallelwith each other.

Also in the case of the embodiment constituted in this way, a timeperiod of simultaneously transmitting the power by the two clutches 39b, 40 b can be produced for a short period of time by prolonging a timeperiod required for switching the two low speed and high speed clutches39 b, 40 b (refer to FIG. 20) from the connected state to thenon-connected state by a simple structure.

Embodiment 11

In Embodiment 8 shown in FIG. 20 or Embodiment 9 shown in FIG. 21, inplace of the throat 103, an electric valve of an electromagnetic valveor the like for cutting flow of the pressurized oil passing the twohydraulic pressure discharge paths on the side of the low speed clutchand on the side of the high speed clutch by a desired period of time canalso be provided. In switching the modes, by making the electric valveclosed for a short period of time (for example, about 0.5 through 2seconds), a time period required for reducing the hydraulic pressure inthe hydraulic chamber with regard to the clutch which has been connectedis ensured and the time period of simultaneously connecting the twoclutches is produced for a short period of time.

In embodying Embodiment 11, the electric valve is controlled to open andclose in accordance with one kind or two or more kinds of requirementsselected from a situation of running the vehicle, that is, a vehiclespeed, an accelerator opening degree, an acceleration degree, adeceleration degree, the torque passing the toroidal-type continuouslyvariable transmission and the like. When the time period of cutting flowof the pressurized oil passing the hydraulic pressure discharging pathby the electric valve is controlled in accordance with the situation ofrunning the vehicle, the impact brought about in changing speed canfurther be alleviated by further finely connecting and disconnecting thetwo clutches.

Embodiment 12

FIGS. 23 through 25B show Embodiment 12 of the invention. In the case ofthe embodiment, the structures of the switching valve 66 a for the lowspeed clutch and the switching valve 70 b for the high speed clutch aremade to differ from those of Embodiment 1 shown in FIGS. 1 through 7,mentioned above. Further, the above-described respective switchingvalves 66 a, 70 b are switched as desired regardless of variations inhydraulic pressures introduced into the respective pilot chambers 69 a,73 a for the low speed clutch and the high speed clutch of therespective switch valves 66 a, 70 b.

For that purpose, in the case of the embodiment, the pilot chamber 69 afor the low speed clutch and the reaction force chamber 109 for the lowspeed clutch are provided at two end portions of the switching valve 66a for the low speed clutch in a state of interposing the spool 67 a forthe low speed clutch from the both sides in the axial direction.Further, pressurized oil delivered from the pressure reducing valve 65is introduced into the reaction force chamber 109 for the low speedclutch. In contrast thereto, a portion of pressurized oil delivered fromthe pressure reducing valve 65 and supplied into the pilot chamber 61for the high speed clutch of the clutch 40 b for high speed via theswitching valve 70 b for the high speed clutch in accordance withswitching of the shifting switching valve 74 is delivered into the pilotchamber 69 a for the low speed clutch. When a pressure receiving areaS_(L1) of the spool 67 a for the low speed clutch on a side of the pilotchamber 69 a for the low speed clutch and a pressure receiving areaS_(L2) of the spool 67 a for the low speed clutch on a side of thereaction force chamber 109 of the low speed clutch are compared, thepressure receiving area on the side of the pilot chamber 69 a for thelow speed clutch is larger (S_(L1)>S_(L2)). Specifically, a ratio of thepressure receiving area S_(L2) on the side of the reaction force chamber109 for the low speed clutch to the pressure receiving area S_(L1) onthe side of the pilot chamber 69 a for the low speed clutch is made tobe equal to or larger than 0.4 and less than 1 (0.4 □S_(L2)/S_(L1)<1).Further, inside of the reaction force chamber 109 for the low speedclutch is provided with the rattle preventing spring 111 of acompression coil spring or the like, the spool 67 a for the low speedclutch is lightly pressed to the side of the hydraulic chamber 69 a forthe low speed clutch. An elastic force of the rattle preventing spring111 is made to be a small value to a degree of preventing rattle of thespool 67 a for the low speed clutch regardless of vibration or the likeaccompanied by running.

Operation of the switching valve 66 a for the low speed clutch havingthe above-described constitution is as follows. First, when the shiftingswitch valve 74 is switched to the low speed mode state as shown by FIG.23, the pilot chamber 69 a for the low speed clutch communicates withthe oil storage 62 and hydraulic pressure is introduced only to thereaction force chamber 109 for the low speed clutch. As a result, thespool 67 a for the low speed clutch is moved to a left end as shown byFIG. 23, and pressurized oil delivered from the pressure reducing valve65 is delivered into the hydraulic chamber 60 for the low speed clutchof the clutch 39 b for low speed. In contrast thereto, when the shiftingswitch valve 74 switched to the high speed mode state, contrary to thestate shown in FIG. 23, pressurized oil is supplied to the hydraulicchamber for the high speed clutch of the clutch 40 b for high speed inaccordance with switching of the switching valve 70 b for the high speedclutch, mentioned below. Further, a portion of the pressurized oil isdelivered to the pilot chamber 69 a for the low speed clutch via theshifting switch valve 74.

As described above, the pressure receiving area of the spool 67 a forthe low speed clutch is larger on the side of the pilot chamber 69 a forthe low speed clutch and smaller on the side of the reaction forcechamber 109 for the low speed clutch and therefore, the spool 67 a forthe low speed clutch is moved to a right end contrary to the state shownin FIG. 23. As a result, the hydraulic chamber for the low speed clutchcommunicates with the oil storage 62 and connection of the clutch 39 bfor low speed is disconnected. At this occasion, an instance ofdisconnecting connection of the clutch 39 b for low speed is slightlyretarded from an instance of connecting the clutch 40 b for high speedsimilar to the case of Embodiment 1, mentioned above.

Further, the pilot chamber 73 a for the high speed clutch and thereaction chamber 110 for the high speed clutch are provided at both endportions of switching valve 70 b for the high speed clutch in a state ofinterposing the spool 71 a for the high speed clutch from both sides inthe axial direction. Further, pressurized oil delivered from thepressure reducing valve 65 is introduced into the reaction chamber 110for the high speed clutch. In contrast thereto, a portion of pressurizedoil delivered from the pressure reducing valve 65 and supplied into thehydraulic chamber 60 for the low speed clutch of the clutch 39 b via theswitching valve 66 a for the low speed clutch in accordance withswitching of the shifting switch valve 74 is delivered into the pilotchamber 73 a for the high speed clutch. When a pressure receiving areaS_(H1) of the spool 71 a for the high speed clutch on a side of thepilot chamber 73 a for the high speed clutch and a pressure receivingarea S_(H2) of the spool 71 a for the high speed clutch on a side of thereaction force chamber 110 for the high speed clutch are compared, thepressure receiving area on the side of the pilot chamber 73 a for thehigh speed clutch is larger (S_(H1)>S_(H2)). Specifically, a ratio ofthe pressure receiving area S_(H2) on the side of the reaction chamber110 for the high speed clutch to the pressure receiving area S_(H1) onthe side of the pilot chamber 73 a for the high speed clutch is made tobe equal to or larger than 0.4 and less than 1 (0.4≦S_(H2)/S_(H1)<1).Further, also inside of the reaction chamber 110 for the high speedclutch is provided with the rattle preventing spring 111 of acompression coil spring or the like similar to the reaction forcechamber 109 for the low speed clutch.

Operation of the switching valve 70 b for the high speed clutch havingthe above-described constitution is as follows. First, when the shiftingswitch valve 74 is switched to the high speed mode state contrary to thestate shown in FIG. 23, the pilot chamber 73 a for the high speed clutchcommunicates with the oil storage 62 and hydraulic pressure isintroduced only to the reaction force chamber 110 for the high speedclutch. As a result, the spool 71 a for the high speed clutch is movedto a right end contrary to the state shown in FIG. 23 and pressurizedoil delivered from the pressure reducing valve 65 is delivered into thehydraulic chamber 61 for the high speed clutch of the clutch 40 b forhigh speed. In contrast thereto, when the shifting switch valve 74 isswitched to the low speed mode state as shown by FIG. 23, pressurizedoil is supplied to the hydraulic chamber 60 of the clutch 39 b for lowspeed in accordance with switching of the switching valve 66 a for thelow speed clutch. Further, a portion of the pressurized oil is deliveredto the pilot chamber 73 a for the high speed clutch via the shiftingswitch valve 74.

As described above, the pressure receiving area of the spool 71 a forthe high speed clutch is larger on the side of the pilot chamber 73 afor the high speed clutch and smaller on the side of the reaction forcechamber 110 for the high speed clutch and therefore, the spool 71 a forthe high speed clutch is moved to a left end as shown by FIG. 23. As aresult, the hydraulic chamber 61 for the high speed clutch communicateswith the oil storage 62 and connection of the clutch 40 b for high speedis disconnected. At this occasion, an instance of disconnectingconnection of the clutch 40 b for high speed is slightly retarded froman instance of connecting the clutch 39 b for low speed similar to thecase of Embodiment 1, mentioned above.

In the case of the embodiment constituted as described above, a basicconstitution is similar to that of Embodiment 1, mentioned above. Adifference therebetween resides in that whereas in the case ofEmbodiment 1, the forces for pressing the respective spools 67 a, 71 afor the low speed clutch and for the high speed clutch constituting therespective switching valves 66 a, 70 b for the low speed clutch and forthe high speed clutch are provided from the respective compression coilsprings 68, 72 (refer to FIG. 3) for the low speed clutch and for thehigh speed clutch, in the case of the embodiment, the forces areprovided by hydraulic pressures introduced into the respective reactionforce chambers 109, 110 for the low speed clutch and for the high speedclutch. By adopting such a constitution, in the case of the embodiment,regardless of variations in the hydraulic pressures, switching of theswitching valve 66 a for the low speed clutch and the switching valve 70b for the high speed clutch can firmly be carried out. An explanationwill be given of the difference in reference to FIGS. 24 through 25.

FIGS. 24A and 24B shows changes in hydraulic pressures in the respectivehydraulic chambers 60, 61 for the low speed clutch and for the highspeed clutch in switching the mode. FIG. 24A shows a theoretical curveand FIG. 24B shows an actually measured result, respectively. Inswitching the mode, in accordance with switching the shifting switchvalve 74, hydraulic pressure of the hydraulic chamber which has beencommunicated with the oil storage 62 starts to rise as shown by a boldline a, simultaneously with introducing the hydraulic pressure into thehydraulic chamber of either one of the clutches which has not beenconnected, the hydraulic pressure is introduced into the pilot chamberof the switching valve for the clutch for disconnecting the other clutchwhich has been connected. However, the rise of the hydraulic pressure inthe pilot chamber becomes stagnant (temporarily lowered as shown by α ofFIG. 24B) during a time period of displacing a constituent member of theclutch for connecting either one of the clutches which has not beenconnected.

Further, when the constituent member of either one of the clutches whichhas not been connected finishes to displace, hydraulic pressureintroduced into the pilot chamber further rises and the hydraulicpressure introduced into the pilot chamber becomes larger than apredetermined pressure shown by a broken line b in FIG. 24A, the spoolfor the clutch starts displacing. The predetermined pressure is aproduct of a pressure P of the pressurized oil delivered from thepressure reducing valve 65 by a ratio of the pressure receiving area ofthe spool for the clutch on the side of the reaction force chamber tothe pressure receiving area on the side of the pilot chamber(P·S_(L2)/S_(L1) or P·S_(H2)/S_(H1)). In this way, when the spool forthe clutch with regard to either one of the clutches which has not beenconnected is displaced and the either one of the clutches starts to beconnected, the hydraulic chamber for the clutch with regard to other ofthe clutches which has been connected is made to communicate with theoil storage 62, hydraulic pressure in the hydraulic chamber for theclutch with regard to other of the clutches which has been connectedstarts to be lowered as shown by a chain line c of FIG. 24A, andconnection of the other of the clutches is disconnected. Further, in theactual case, hydraulic pressure in the hydraulic chamber for the clutchwith regard to other of the clutches is temporarily lowered andthereafter rises and starts to lower again as shown by a chain line c inFIG. 24B. The reason of lowering the hydraulic pressure in the hydraulicchamber for the clutch with regard to other of the clutches temporarilyin this way is that pressurized oil is consumed for displacing theconstituent member of one of the clutches.

At any rate, as is apparent from the bold lines a and chain lines c ofFIGS. 24A and 24B, in connecting and disconnecting the one and the otherclutches, there is present an instance of connecting the both clutches.Therefore, as is apparent from the explanation of a portion ofEmbodiment 1, mentioned above, unpleasant feeling is not given to apassenger including a driver by bringing about speed changing shock orthe like in switching the mode. Further, since there is not present theinstance in which both of the clutches are not connected, the rotationalspeed of the engine under a no load state does not rise rapidly (overrotated). Further, such a rapid rise of the rotational speed of theengine brings about large impact at an instance of connecting either ofthe clutches thereafter, gives unpleasant feeing to a passenger andcauses to deteriorate durabilities of respective constituent members ofthe continuously variable transmission apparatus. According to theinvention including the embodiment, such a drawback is not broughtabout.

Further, in the case of the embodiment, even when hydraulic pressure ofpressurized oil delivered from the pressure reducing valve 65 is variedby some cause, the respective clutches can firmly be connected anddisconnected. That is, regardless of a variation in the hydraulicpressure, after connecting the clutch which has not been connected,connection of the clutch which has been connected can be disconnected.For example, as a result of lowering the hydraulic pressure, hydraulicpressure introduced into the hydraulic chamber with regard to one of theclutches is changed from the bold line a to a broken line d, thepredetermined pressure of starting to displace the spool for the clutchwith regard to one of the clutches is lowered to the position of abroken line e from the position of the broken line b of FIG. 24A.Further, the two clutches can be connected and disconnected similar to acase in which the hydraulic pressure is not lowered. In this respect, inthe case of the embodiment, reliability can be improved in comparisonwith a case of Embodiment 1, mentioned above, in which hydraulicpressures for switching the respective switching valves 66, 70 for thelow speed clutch and for the high speed clutch are restricted by theelastic forces of the respective compression coil springs 68, 72 (referto FIG. 3) for the low speed clutch and for the high speed clutch.

The respect will be explained in reference to FIG. 25. A bold line α inFIG. 25 indicates hydraulic pressure of a portion of the hydraulicchamber for the clutch with regard to one of the clutches which has notbeen connected, a broken line β of the same indicates hydraulic pressurefor switching the switching valve for the clutch, and a chain line γ ofthe same indicates hydraulic pressure of a portion of the hydraulicchamber for the clutch with regard to other clutch which has beenconnected, respectively. In the case of a structure of Embodiment 1, asshown by FIG. 25A, no problem is posed when a relationship betweenhydraulic pressure of switching the switching valve for the clutch andhydraulic pressure introduced into a portion of the hydraulic chamberfor each clutch is pertinent. In contrast thereto, when hydraulicpressure for switching the switching valve for the clutch is excessivelylower than hydraulic pressure introduced into the portion of thehydraulic chamber for the clutch such that the elastic forces of therespective compression coil springs 68, 72 are excessively low, or thehydraulic pressures introduced into the portions of the hydraulicchambers of the respective clutches are excessively high, (switching ofthe switching valve for the clutch is carried out excessively simply),the hydraulic pressures are shown by FIG. 25B. In this case, there ispresent an instance of simultaneously disconnecting connection of thetwo clutches to bring about speed changing shock. Further, whenhydraulic pressure for switching the switch valve for the clutch isexcessively higher than the hydraulic pressure introduced into theportion of the hydraulic chamber for each clutch (a switching valve forthe clutch is difficult to be switched) such that the elastic forces ofthe respective compression springs are excessively high or hydraulicpressures introduced into the portions of the hydraulic chambers of therespective clutches are excessively low, the hydraulic pressures becomesas shown by FIG. 25(C). In this case, even when a signal for theswitching mode is outputted, the respective clutches 39 b, 40 b for lowspeed and for high speed (refer to FIG. 3) are not connected nordisconnected.

In the case of Embodiment 1, described above, it is necessary topertinently restrict the set pressure of the pressure reducing valve 65and the elastic forces of the respective compression coil springs 68, 72such that such a problem is not posed. Further, it is necessary toselect constituent members including materials thereof such that the setpressure or the elastic forces are not varied even by using theconstituent elements over a long period of time. In contrast thereto, inthe case of the embodiment, even when such a consideration is not given,the respective clutches 39 b, 40 b for the low speed and high speed canpertinently be connected and disconnected.

Embodiment 13

FIG. 26 shows Embodiment 13 of the invention. The embodiment isconstituted by a structure of combining Embodiment 6 shown in FIG. 16,mentioned above, with Embodiment 12 shown in FIGS. 23 through 25,mentioned above. That is, in the case of the embodiment, hydraulicpressure delivered from the pressurizing pump 63 on the high-pressureside and passed through the pressure reducing valve 65 is introducedinto the two reaction force chambers 109, 110 for the low speed clutchand for the high speed clutch in accordance with opening theelectromagnetic valves 117 a, 117 b. In the case of the embodiment, inswitching the mode, by opening the respective electromagnetic valves 117a, 117 b in order to increase the value opening pressures of therespective switching valves 66 a, 70 b for the low speed clutch and forthe high-speed clutch in switching the mode, hydraulic pressures areintroduced into the respective reaction force chambers 109, 110.Further, in starting, hydraulic pressures in the respective reactionforce chambers 109, 110 are discharged by closing the respectiveelectromagnetic valves 117 a, 117 b in order to lower the valve openingpressures of the respective switching valves 66 a, 70 b for the lowspeed clutch and for the high speed clutch. The control of theelectromagnetic valves 117 a, 117 b can also be carried out based on thetransmission ratio of the toroidal type continuously variabletransmission 24, 24 a (refer to FIG. 1 and the like) other than carryingout based on the vehicle speed. That is, the transmission ratio of thetoroidal type continuously variable transmission 24, 24 a differssignificantly between in starting and in switching the mode. Therefore,when the control of the respective electromagnetic valves 117 a, 117 bis carried out based on the transmission ratio of the toroidal typecontinuously transmission 24, 24 a, when the transmission ratio becomesproximate to a value of switching the mode, pressurized oil may beintroduced into the respective reaction force chambers 109, 110 byopening the respective electromagnetic valves 117 a, 117 b. Whenconstituted in this way, in switching the mode, there can be provided atime period of simultaneously transmitting power by the two clutches 39b, 40 b for low speed and for high speed (an instance of disconnectingconnection of one clutch is slightly retarded from an instance ofconnecting other clutch) and further, the clutch which is not to beconnected in starting can be prevented from being connected. The otherconstitutions and operation are similar to those of Embodiment 12,mentioned above, and Embodiment 6, mentioned above. In theabove-described explanation, an explanation has been given of the caseof applying the invention to the continuously variable transmissionapparatus referred to as the geared neutral type realizing a rearwardmoving state, a stationary state and a forward moving state withoutswitching the clutches by combining the toroidal-type continuouslyvariable transmission and the planetary gear type transmission. However,the invention is applicable also to the structure integrated to thecontinuously variable transmission apparatus referred to as so-to-speakpower split type for transmitting power only by the toroidal-typecontinuously variable transmission in running at low speed, transmittingmain power by the planetary gear type transmission in running at highspeed and controlling the transmission ratio by the toroidal-typecontinuously variable transmission. Further, the invention can beutilized not only as an automatic transmission for an automobile butalso as a transmission for various industries. Further, the type of thetoroidal continuously transmission apparatus is not limited to ahalf-toroidal type continuously variable transmission apparatus as shownin the drawings. The invention can be applied to a full-toroidal typecontinuously variable transmission apparatus.

1. A continuously variable transmission apparatus combined with atoroidal continuously variable transmission and a planetary geartransmission via a clutch apparatus, wherein the clutch apparatuscomprising: a low speed clutch connected in realizing a low speed modeof increasing a gear change ratio of the continuously variabletransmission apparatus and disconnected in realizing a high speed modeof reducing the gear change ratio of the continuously variabletransmission apparatus; a high speed clutch connected in realizing thehigh speed mode and disconnected in realizing the low speed mode; and acontroller for switching a state of connecting and disconnecting therespective clutches; and wherein the controller brings a speed changestate into either mode of the low speed mode and the high speed mode bycontrolling to connect and disconnect the respective clutches; and thecontroller has a function, in switching the low speed mode and the highspeed mode, that, prior to start to connect one of the low speed clutchand the high speed clutch which has not been connected, by adjusting thetransmission ratio of the toroidal continuously variable transmission,the one clutch is started to connect after making rotational speeds of apair of members connected via the one clutch substantially coincide witheach other, and after starting to transmit a power by the one clutch, anoperation of disconnecting other clutch which has been connected isstarted, whereby an instance of simultaneously transmitting the power bythe two clutches is set during a time period until disconnecting theother clutch after starting to transmit the power by the one clutch. 2.The continuously variable transmission apparatus according to claim 1,wherein a start of the power transmission by the one clutch is detectedby detecting a displacement of a drive member for connecting the clutch.3. The continuously variable transmission apparatus according to claim1, wherein the low speed clutch is connected by introducing a hydraulicpressure into a hydraulic chamber for the low speed clutch; the highspeed clutch is connected by introducing a hydraulic pressure into ahydraulic chamber for the high speed clutch; and a start of the powertransmission by the one of the low speed clutch and the high speedclutch is detected by the hydraulic pressure in the hydraulic chamberfor the clutch for introducing the hydraulic pressure in connecting theclutch.
 4. The continuously variable transmission apparatus according toclaim 3, wherein the hydraulic pressure in the hydraulic chamber for theclutch is electrically detected by a pressure sensor.
 5. Thecontinuously variable transmission apparatus according to claim 3,further comprising: a switching valve switched by introducing thehydraulic pressure into the hydraulic chamber for the clutch tomechanically detect the hydraulic pressure in the hydraulic chamber forthe clutch; wherein a spool constituting the switching valve isdisplaced by introducing the hydraulic pressure into the hydraulicchamber for the clutch and the hydraulic pressure introduced into thehydraulic chamber for the clutch of the other clutch is reduced based ona displacement of the spool.
 6. The continuously variable transmissionapparatus according to claim 5, wherein a state of introducing thehydraulic pressure into the hydraulic chamber for the low speed clutchis controlled by the switching valve for the low speed clutch includinga spool for the low speed clutch displaced by introducing the hydraulicpressure into a pilot chamber for the low speed clutch; a state ofintroducing the hydraulic pressure into the hydraulic chamber for thehigh speed clutch is controlled by the switching valve for the highspeed clutch including a spool for the high speed clutch displaced byintroducing the hydraulic pressure into a pilot chamber for the highspeed clutch; the state of introducing the hydraulic pressure into thepilot chamber for the low speed clutch and the state of introducing thehydraulic pressure into the pilot chamber for the high speed clutch arecontrolled by an electric switch valve; the switching valve for the lowspeed clutch reduces the hydraulic pressure introduced into thehydraulic chamber for the low speed clutch by introducing the hydraulicpressure into the pilot chamber for the low speed clutch; the hydraulicpressure introduced into the pilot chamber for the low speed clutch isthe hydraulic pressure introduced into the hydraulic chamber for thehigh speed clutch; the switching valve for the high speed clutch reducesthe hydraulic pressure introduced into the hydraulic chamber for thehigh speed clutch by introducing the hydraulic pressure into the pilotchamber for the high speed clutch; and the hydraulic pressure introducedinto the pilot chamber for the high speed clutch is the hydraulicpressure introduced into the hydraulic chamber for the low speed clutch.7. The continuously variable transmission apparatus according to claim5, wherein a state of introducing the hydraulic pressure into thehydraulic chamber for the low speed clutch is controlled by the switchvalve for the low speed clutch including a spool for the low speedclutch displaced by introducing the hydraulic pressure into a pilotchamber for the low speed clutch; a state of introducing the hydraulicpressure into the hydraulic chamber for the high speed clutch iscontrolled by the switching valve for the high speed clutch including aspool for the high speed clutch displaced by introducing the hydraulicpressure into a pilot chamber for the high speed clutch; the state ofintroducing the hydraulic pressure into the pilot chamber for the lowspeed clutch and the state of introducing the hydraulic pressure intothe pilot chamber for the high speed clutch are controlled by a shiftingswitching valve including a switching spool displaced by introducing thehydraulic pressure into a switching pilot chamber; a state ofintroducing the hydraulic pressure into the switching pilot chamber iscontrolled by a shifting electric switching valve, the switching valvefor the low speed clutch reduces the hydraulic pressure introduced intothe hydraulic chamber for the low speed clutch by introducing thehydraulic pressure into the pilot chamber for the low speed clutch; thehydraulic pressure introduced into the pilot chamber for the low speedclutch is the hydraulic pressure introduced into the hydraulic chamberfor the high speed clutch; the switching valve for the high speed clutchreduces the hydraulic pressure introduced into the hydraulic chamber forthe high speed clutch by introducing the hydraulic pressure into thepilot chamber for the high speed clutch; and the hydraulic pressureintroduced into the pilot chamber for the high speed clutch is thehydraulic pressure introduced into the hydraulic chamber for the lowspeed clutch.
 8. The continuously variable transmission apparatusaccording to claim 7, wherein a shifting manual switching valve formanually achieving a function the same as a function of the shiftingelectric switching valve is provided in parallel with the shiftingelectric switching valve and a selecting manual switching valve forselecting either of the shifting electric switching valve and theshifting manual switching valve is provided.
 9. The continuouslyvariable transmission apparatus according to claim 7, wherein theswitching valve for the high speed clutch includes an elastic member forthe high speed clutch on a side opposed to the pilot chamber for thehigh speed clutch in an axial direction by interposing the spool for thehigh speed clutch; the spool for the high speed clutch is displacedagainst an elastic force of the elastic member for the high speed clutchby introducing the hydraulic pressure into the pilot chamber for thehigh speed clutch; the switching valve for the low speed clutch includesan elastic member for the low speed clutch on a side opposed to thepilot chamber for the low speed clutch in an axial direction byinterposing the spool for the low speed clutch; and the spool for thelow speed clutch is displaced against an elastic force of the elasticmember for the low speed clutch by introducing the hydraulic pressureinto the pilot chamber for the low speed clutch.
 10. The continuouslyvariable transmission apparatus according to claim 9, wherein theelastic force of the elastic member for the clutch integrated to theswitching valve for the clutch opened in introducing the hydraulicpressure into the hydraulic chamber for the clutch belonging to theclutch which is not to be connected at least in starting in therespective switching valves for the low speed and the high speedclutches is set to be large in a running state and small in anon-running state.
 11. The continuously variable transmission apparatusaccording to claim 10, wherein the elastic member for the clutch is acompression coil spring for the clutch, the compression coil spring forthe clutch is provided between the spool for the clutch and a pressingpiston provided displaceably in the axial direction at inside of acylinder portion provided at a position opposed to the pilot chamber forthe clutch in the axial direction by interposing the spool for theclutch, and the pressing piston increases the elastic force of thecompression coil spring for the clutch by being displaced to a side ofthe spool for the clutch by the hydraulic pressure introduced into thecylinder portion when the running state is selected and reduces theelastic force of the compression coil spring for the clutch by beingdisplaced to a side of being remote from the spool for the clutch whenthe hydraulic pressure in the cylinder portion is discharged byselecting the non-running state.
 12. The continuously variabletransmission apparatus according to claim 11, further comprising: amanual switching valve switched to a running mode and a non-running modeby a shift lever installed at a driver's seat; wherein also the elasticforces of the elastic members for the clutches integrated to theswitching valves for the clutches opened in introducing the hydraulicpressure into the hydraulic chambers for the clutches belonging not onlyto the clutch which is not to be connected in starting but also theclutch which is to be connected in starting for elastically pressing thespools for the clutches in the respective switching valves for the lowspeed and the high speed clutches are increased in a state of switchingthe manual switching valve to the running mode and reduced in a state ofswitching the manual switching valve to the non-running mode.
 13. Thecontinuously variable transmission apparatus according to claim 7,wherein the switching valve for the clutch opened in introducing thehydraulic pressure into the hydraulic chamber for the clutch belongingto the clutch which is not to be connected at least in starting in therespective switching valves for the low speed clutch and the high speedclutch, is provided with a reaction force chamber on a side opposed tothe pilot chamber for the clutch constituting the switching valve forthe clutch by interposing the spool for the clutch constituting theswitching valve for the clutch, and the hydraulic pressure in thereaction force chamber for pressing the spool for the clutch to a sideof the pilot chamber for the clutch based on the hydraulic pressureintroduced to inside of the reaction force chamber is set to be large inthe running state and small in the non-running state.
 14. Thecontinuously variable transmission apparatus according to claim 13,wherein the hydraulic pressure having a reduced pressure by beingdelivered from a delivery port of a pressurizing pump and passing apressure reducing valve is introduced into the reaction force chamber bypassing a pressure control valve of an electric type or an opening andclosing valve.
 15. The continuously variable transmission apparatusaccording to claim 13, wherein the hydraulic pressure having a reducedpressure by being delivered from a delivery port of pressurizing pumpand passing a pressure reducing valve is introduced into the reactionforce chamber by passing a valve of a hydraulic type switched based onthe hydraulic pressure in the hydraulic chamber for the clutch belongingto the connected clutch in the high speed clutch and the low speedclutch.
 16. The continuously variable transmission apparatus accordingto claim 13, further comprising: a manual switching valve switched to arunning mode and a non-running mode by a shift lever installed at adriver's seat; wherein also the hydraulic pressures in the reactionchambers of the switching valves for the clutches opened in introducingthe hydraulic pressure into the hydraulic chambers for the clutchesbelonging not only to the clutch which is not to be connected instarting but also the clutch which is to be connected in starting in therespective switching valves for the low speed and the high speedclutches are increased in a state of switching the manual switchingvalve to the running mode and reduced in a state of switching the manualswitching valve to the non-running mode.
 17. The continuously variabletransmission apparatus according to claim 13, wherein the hydraulicpressure outputted from a portion communicating with a delivery port ofa pressurizing pump and adjusted to a predetermined pressure by apressure control valve of an electric type is introduced into thereaction force chamber.
 18. The continuously variable transmissionapparatus according to claim 7, wherein the switching valve for the highspeed clutch includes a reaction force chamber for the high speed clutchon a side opposed to the pilot chamber for the high speed clutch in anaxial direction by interposing the spool for the high speed clutch, thespool for the high speed clutch is displaced against the hydraulicpressure introduced into the reaction force chamber for the high speedclutch by introducing the hydraulic pressure into the pilot chamber forthe high speed clutch, the switching valve for the low speed clutchincludes a reaction force chamber for the low speed clutch on a sideopposed to the pilot chamber for the low speed clutch in an axialdirection by interposing the spool for the low speed clutch, and thespool for the low speed clutch is displaced against the hydraulicpressure introduced into the reaction force chamber for the low speedclutch by introducing the hydraulic pressure into the pilot chamber forthe low speed clutch.
 19. The continuously variable transmissionapparatus according to claim 18, wherein a rattle preventing spring forthe high speed clutch for pressing the spool for the high speed clutchto the side of the pilot chamber for the high speed clutch is providedin the reaction force chamber for the high speed clutch, and a rattlepreventing spring for the low speed clutch for pressing the spool forthe low speed clutch to the side of the pilot chamber for the low speedclutch is provided in the reaction force chamber for the low speedclutch, respectively.
 20. The continuously variable transmissionapparatus according to claim 18, wherein a pressure receiving area on aside of the pilot chamber for the high speed clutch in the spool for thehigh speed clutch is wider than a pressure receiving area on a side ofthe reaction force chamber for the high speed clutch; the same hydraulicpressure is made to be able to be introduced into the hydraulic chamberfor the high speed clutch and the reaction force chamber for the highspeed clutch; a pressure receiving area on a side of the pilot chamberfor the low speed clutch in the spool for the low speed clutch is widerthan a pressure receiving area on a side of the reaction force chamberfor the low speed clutch; and the same hydraulic pressure is made to beable to be introduced into the pilot chamber for the low speed clutchand the reaction force chamber for the low speed clutch.
 21. Thecontinuously variable transmission apparatus according to claim 18,wherein the hydraulic pressure introduced into the pilot chamber for thehigh speed clutch, the reaction force chamber for the high speed clutch,the pilot chamber for the low speed clutch, and the reaction forcechamber for the low speed clutch is the hydraulic pressure introducedinto the two hydraulic chambers for the high speed clutch and the lowspeed clutch.
 22. The continuously variable transmission apparatusaccording to claim 20, wherein a ratio of the pressure receiving area onthe side of the reaction force chamber for the high speed clutch to thepressure receiving area on the side of the pilot chamber for the highspeed clutch as well as a ratio of the pressure receiving area on theside of the reaction force chamber for the low speed clutch to thepressure receiving area on the side of the pilot chamber for the lowspeed clutch are both equal to or larger than 0.4 and less than 1.